Opinion

BROWN (G. A.), P. J

This cause is before us on a petition for a writ of mandamus filed pursuant to Penal Code section 1538.5 after petitioner’s motion to suppress was denied by the trial court. He is charged with violating Health and Safety Code section 11357 (possession of marijuana). The evidence he seeks to suppress is that which a police officer visualized and the fruits thereof when the officer peeked through an aperture in a Venetian blind into a closed business establishment at about 8:40 p.m. on March 27, 1973.

*492 Sanders’ Meat and Locker Service is a retail business located at 1220 South Avenue in the City of Turlock. There is a customer parking area in front of the building. The front entrance consists of two double swinging, uncovered glass doors leading into the lobby. To the left of the lobby is a workroom which has a large plate glass window facing the parking lot. Beneath that window, between the edge of the paved parking lot and the wall, is a planter area about three feet wide which is substantially flush with the parking lot pavement. The planter area is not a common walkway or pathway. The rest of the building consists of offices, locker space and processing plant.

On March 17, 1973, at about 7:40 p.m., Officer Lilly of the Turlock Police Department was on routine patrol in the area of the Sanders’ Meat and Locker Service. As he passed the Sanders building he noticed a light blue Mustang parked in the parking lot adjacent to the building. He recognized the vehicle, having seen it parked there on many prior occasions during the daytime. He was not sure whether he had previously seen this vehicle parked there at that hour of the evening. He also noticed that a light was on in the area of the building later identified as the workroom. Although the business was closed for the day, these circumstances alone did not arouse his concern for the safety of the building.

At about 8:40 p.m. Officer Lilly again drove by the Sanders building. This time he noticed a second car parked in the lot near the blue Mustang and also noticed that the light in the workroom was still on. There was nothing unusual or suspicious about the way the cars were parked. The additional factor, however, of a second car being parked there aroused his concern for the safety of the building. Consequently, he notified Sergeant Mueller by radio and informed him of the situation. The two officers met about a quarter of a mile away from the building for the purpose of discussing the matter, and at that time Officer Lilly disclosed to Officer Mueller what he described as suspicious circumstances at the building.

The two officers then proceeded to the Sanders building and parked their patrol cars near the other two vehicles in the parking lot. They did not attempt to notify Mr. Sanders though they knew he was the owner of the building. As Sergeant Mueller emerged from his patrol car he heard music, loud conversation and laughter coming from the portion of- the building where the light was on. Sergeant Mueller then went to the window where the noise was coming from to investigate the situation. In doing so he walked across the parking lot and, in order to look through the window, stepped onto the planter area.

*493 The large plate glass window at the front of the workroom was covered by sheer curtains and Venetian blinds which were drawn completely closed. Sergeant Mueller stated that from the way the blinds were situated there had been an obvious effort to close them completely.

Due to an apparent defect in the Venetian blinds there was an opening or aperture in the blinds of about one and one-half to two inches at approximately eye level. By standing in the planter area no more than a foot away from the window, Sergeant Mueller could see into the workroom. He saw petitioner and one Thomas Volk 1 smoking marijuana. He would not have been able to observe this activity if the blinds had not been defective and if he had not been within a foot of the window.

After Sergeant Mueller had observed petitioner and Volk smoking marijuana for a short time, Volk left the workroom and entered the lobby area, whereupon Mueller gained his attention and had him open the front door from the inside. Petitioner and Volk were then placed under arrest. As a result of a subsequent search of the workroom the officers picked up marijuana and various items of paraphernalia, all of which is sought to be suppressed as the poisonous fruit of the illegal viewing by Sergeant Mueller.

We are, of course, bound by the factual findings of the trial court. However, the trial court also has the duty to decide whether, on the facts found, the search was unreasonable within the meaning of the Constitution. “ . . Although that issue is a question of law, the trial court's conclusion on the point should not lightly be challenged by appeal or by petition for extraordinary writ. (Fn. omitted.) Of course, if such review is nevertheless sought, it becomes the ultimate responsibility of the appellate court to measure the facts, as found by the trier, against the constitutional standard of reasonableness.’ (Italics added; [citation].)’’ (People v. Gale (1973) 9 Cal.3d 788, 793 [108 Cal.Rptr. 852, 511 P.2d 1204].)

Following this mandate, we have concluded as a matter of law that the facts and circumstances did not warrant the surreptitious peering into the window by the officer.

The basic test as to whether there has been an unconstitutional .invasion of privacy is whether the person has exhibited a subjective expectation of privacy which is objectively reasonable and, if so, whether *494 that expectation has been violated by unreasonable governmental intrusion. (People v. Bradley (1969) 1 Cal.3d 80, 84-86 [81 Cal.Rptr. 857, 460 P.2d 129]; People v. Edwards (1969) 71 Cal.2d 1096, 1100 [80 Cal.Rptr. 633, 458 P.2d 713].) This test of reasonableness is dependent upon the totality of facts and circumstances involved in the context of each case. (North v. Superior Court (1972) 8 Cal.3d 301, 308-312 [104 Cal.Rptr. 833, 502 P.2d 1305, 57 A.L.R.3d 155]; Dillon v. Superior Court (1972) 7 Cal.3d 305, 310-311 [102 Cal.Rptr. 161, 497 P.2d 505]; People v. Sneed (1973) 32 Cal.App.3d 535, 540 [108 Cal.Rptr. 146].)

As to the first of the two facets of this test, we readily conclude that petitioner did exhibit a subjective expectation of privacy which was objectively reasonable. While under some conceivable circumstances there may be a difference between a private residence and a business establishment, under the facts here no rational foundation for such a distinction appears. 2

Credible authority supports this conclusion. In Katz v. United States (1967) 389 U.S. 347, 351 [19 L.Ed.2d 576, 582, 88 S.Ct. 507], the court said: “[T]he Fourth Amendment protects people, not places. What a person knowingly exposes to the public, even in his own home or office, is not a subject of Fourth Amendment protection. [Citations.] But what he seeks to preserve as private, even in an area accessible to the public, may be constitutionally protected.”

In People v. Dumas (1973) 9 Cal.3d 871, 881-882 [109 Cal.Rptr. 304, 512 P.2d 1208], our Supreme Court recently instructed: “The pattern of prior decisions suggests that one of the most crucial determinants of the validity of warrantless searches is the nature of the place subjected to search. This pattern has been created by the interweaving of constitutional concepts with fundamental human needs and expectations. The courts have implicitly recognized that man requires some sanctuary in which his freedom to escape the intrusions of society is all but absolute. [Fn. omitted.] Such places have been held inviolate from warrantless search except in emergencies of overriding magnitude, such as pursuit of a fleeing felon *495 [citation] or the necessity of action for the preservation of life or property [citations].4 ***8”

Footnote 8 provides: “Homes and offices clearly fall within this category of maximum protection [citations] as do hotel rooms [citations].” (Italics added.) (See Dean v. Superior Court (1973) 35 Cal.App.3d 112, 117 [110 Cal.Rptr. 585].)

Had the owner been in the workroom at night with the shades drawn to shut out peering eyes, his subjective expectation of privacy would have been objectively reasonable whether his purpose was to carry on a tryst, do after-hours work, or engage in any other activities, legal or illegal. We perceive no distinction in this connection between the petitioner and the owner as there is no evidence that petitioner’s presence on the premises was other than as the invitee of an employee of the owner.

The existence of the aperture due to a defect in the blinds does not dispel the reasonableness of the expectation of privacy. As was said in Lorenzana v. Superior Court (1973) 9 Cal.3d 626, 636 [108 Cal.Rptr. 585, 511 P.2d 33]: “The fact that apertures existed in the window, so that an unlawfully intruding individual so motivated could spy into the residence, does not dispel the reasonableness of the occupant’s expectation of privacy. [Citations.] To the contrary, the facts of this case demonstrate that by drawing the window shade petitioner . . . exhibited a reasonable expectation to be free from surveillance conducted from a vantage point in the surrounding property not open to public or common use.” (See Pate v. Municipal Court (1970) 11 Cal.App.3d 721, 724 [89 Cal.Rptr. 893].)

Passing to the second and more difficult facet of the test relating to the police officer’s conduct, we must determine whether his actions constituted unreasonable governmental intrusion into the privacy of the workroom.

The Attorney General asserts that the circumstances confronting the officers amounted to an emergency situation which permitted them to conduct their surveillance without a warrant.

It is well settled that emergencies of overriding magnitude may justify a search conducted without prior judicial approval. (See e.g., Warden v. Hayden (1967) 387 U.S. 294 [18 L.Ed.2d 782, 87 S.Ct. 1642] —pursuit of a fleeing felon; People v. Roberts (1956) 47 Cal.2d 374, *496 377 [303 P.2d 721]—moaning sound from person in distress in apartment; People v. Sirhan (1972) 7 Cal.3d 710, 735-741 [102 Cal.Rptr. 385, 497 P.2d 1121], cert. den. 410 U.S. 947 [35 L.Ed.2d 613, 93 S.Ct. 1382]— murder of presidential candidate and fear of conspiracy to kill other political leaders; People v. Gonzales (1960) 182 Cal.App.2d 276 [5 Cal.Rptr. 920] —search of man for identification who was suffering from serious abdominal stab wounds; see also Carrington v. Superior Court (1973) 31 Cal.App.3d 635, 639-640 [107 Cal.Rptr. 546].)

However, where the circumstances confronting the officers do not justify the action taken, the courts have not hesitated to suppress evidence obtained as a result of that action. (See Horack v. Superior Court (1970) 3 Cal.3d 720, 727 [91 Cal.Rptr. 569, 478 P.2d 1]; Mozzetti v. Superior Court (1971) 4 Cal.3d 699, 706-707 [94 Cal.Rptr. 412, 484 P.2d 84]; Flack v. Municipal Court (1967) 66 Cal.2d 981, 991 [59 Cal.Rptr. 872, 429 P.2d 192].)

In making this determination, the courts have been careful to weigh the competing interests of the individual’s privacy, the magnitude of the intrusion, and the degree of the necessity. As recently stated in People v. Little (1973) 33 Cal.App.3d 552, 557 [109 Cal.Rptr. 196]: “A balancing process is inevitably involved in which the magnitude of the officer’s error is weighed against the magnitude of the intrusion of the suspect’s privacy.”

In the case at bench there was no emergency situation of overriding magnitude. Obviously the officers did not subjectively believe that there was such an emergency or that the building was imminently endangered. The light in the building and one car aroused no suspicion. The light- and two cars caused the officer to believe that further investigation was warranted. However, he did so in a rather leisurely way—by meeting another officer a quarter of a mile from the building and then parking the police cars on the parking lot in plain view. Furthermore, the loud noises associated with levity from the interior of the workroom surely dispelled any notion that the occupants were engaged in a burglary. As stated in Horack v. Superior Court (1970) 3 Cal.3d 720, 727 [91 Cal.Rptr. 569, 478 P.2d 1]: “[I]t would be most unusual for an unauthorized intruder to call attention to his presence with a musical accompaniment.” (See also People v. Stephens (1967) 249 Cal.App.2d 113 [57 Cal.Rptr. 66].)

The surveillance of Sergeant Mueller would have been lawful if it had not been necessary to step into the small planter area between the building and the parking lot. For if the surveillance had been conducted from a vantage point where the officer had a right to be the observation would *497 come under the plain sight rule and thus not be considered a search. (See People v. Boone (1969) 2 Cal.App.3d 66, 69 [82 Cal.Rptr. 398]; People v. Anderson (1968) 266 Cal.App.2d 125, 131 [71 Cal.Rptr. 827]; People v. Willard (1965) 238 Cal.App.2d 292, 299 [47 Cal.Rptr. 734].) Accordingly, the short distance that Sergeant Mueller moved into the planter area to reach the window, though unlawful, was a relatively minor intrusion. (People v. Willard, supra, 238 Cal.App.2d 292, 299.) Nevertheless, the degree of the alleged “exigency” confronting the officers was likewise insignificant and thus does not overcome the illegality of their action.

Our Supreme Court, whose determinations we must follow, has refused to put its imprimatur upon surreptitious peeking where there is no overriding exigency or emergency and there are other plausible alternatives available. (People v. Triggs (1973) 8 Cal.3d 884 [106 Cal.Rptr. 408, 506 P.2d 232]; Lorenzana v. Superior Court, supra, 9 Cal.3d 626.)

In Triggs, the police made clandestine observations of homosexual activity in an open public toilet stall from a plumbing access room; the court condemned the observations primarily due to the method of observation, because “[h]is clandestine observation of defendant, ‘ “prompted by a general curiosity to ascertain what, if anything,” ’ was going on within the restroom, was ‘manifestly exploratory in nature, and violates both the letter and spirit of the Fourth Amendment.’ [Citation.]” (8 Cal.3d at p. 895.)

Similarly, in Lorenzana, the court suppressed evidence obtained as a result of police peering through a two-inch aperture between drawn blinds and a windowsill while standing about six inches from the window in an area that was not a normal access route to the home.

In determining the reasonableness of the method selected by the police in conducting further investigation of suspicious circumstances, their surreptitious peeping through the window must be considered in light of alternative available courses of action. In this case, for example, the officer's conduct must be weighed against the alternatives of determining if the front door was locked, of attempting to visualize the activity through the uncovered front doors, of knocking on the front door to obtain entry and of calling police headquarters to have the owner contacted.

We do not hold that upon observing two cars parked on the premises and the lights on in the workroom the police were not justified in concluding that these were suspicious circumstances calling for further investigation; indeed, they might have been derelict in their duty if they had not done so. *498 (People v. Parra (1973) 30 Cal.App.3d 729, 732-734 [106 Cal.Rptr. 531]; People v. Rhodes (1971) 21 Cal.App.3d 10, 19 [98 Cal.Rptr. 249]; People v. Hidalgo (1970) 7 Cal.App.3d 525, 529 [86 Cal.Rptr. 660].) Nor do we deprecate the important responsibility of police officers as guardians of the security of the community and their function in protecting society against the criminal element who live by preying upon law-abiding citizens. (People v. Murphy (1959) 173 Cal.App.2d 367, 375-378 [343 P.2d 273].) We hold only that upon the particular facts of this case, where no overriding emergency or exigency was present and any suspicion of activity involving jeopardy to life or property should have been dispelled by the laughter, loud conversation and music from within, the officers did not act reasonably in walking into the planter area and surreptitiously peeking inside the building through the small aperture caused by a defect in the Venetian blinds. That action was an unreasonable invasion of petitioner’s privacy in violation of Fourth Amendment proscriptions.

The order to show cause is discharged.

Let a peremptory writ issue directing respondent superior court to suppress the testimony of Sergeant Mueller with respect to that which he viewed through the window of the workroom and the evidence seized as the fruit of that activity.

Gargano, J., and Franson, J., concurred.

A petition for a rehearing was denied January 21, 1974, and the petition of the real party in interest for a hearing by the Supreme Court was denied March 8, 1974. McComb, J., Burke, J., and Clark, J., were of the opinion that the petition should be granted.

QUINN, Justice.

Joseph Raymond Gomez (defendant) appeals his conviction for possession of a narcotic drug for sale in violation of section 12-22-322(l)(a), C.R.S.1973 (1978 Repl. Vol. 5). 1 He asserts several grounds for reversal including the trial court’s refusal to suppress evidence seized in the course of a warrantless entry into his motel room, various evidentiary rulings made by the court during the trial, the court’s instruction on the statutory definition of sale and its refusal to give certain tendered instructions to the jury, and the alleged insufficiency of the evidence to support his conviction. We affirm the conviction.

I. The District Court Proceedings

The information charged that the defendant on November 11, 1977, unlawfully possessed for sale a narcotic drug, heroin, with the specific intent to induce or aid another person to unlawfully use or possess the heroin. The charge arose out of the defendant’s arrest in the early morning hours of November 11, 1977, at the Sunset Village Motel in Lakewood, Colorado.

During the month preceding the defendant’s arrest the management of the motel had experienced a series of thefts from the motel units. The manager noticed that four persons registered at the motel on several occasions under different names and the thefts usually occurred during their stay there. Agent Shilaos of the Lakewood Department of Public Safety advised the manager to notify him if any of the four persons registered at the motel again. During the evening of November 10, 1977, the defendant’s companion, Joseph Herrera, who was one of the four suspects, registered at the motel and occupied unit 17 with the defendant. Upon being notified of this by the manager, Agents Shilaos and Shaw went to the motel to talk to Herrera about the thefts. Shilaos was dressed in plain clothes and Shaw was in uniform.

Unit 17 is a rectangular bedroom with a shower and toilet. It is approximately twenty-four feet in length from east to west and twelve feet deep. The front door opens on the north side to a sidewalk or entrance way which extends along the entire front of the unit. There are two large casement windows in the northwest corner of the unit, both of which are located at normal eye level. One window faces north and directly overlooks the sidewalk and the other faces west and overlooks the sidewalk at a slight angle. The windows had curtains but the curtains on the window facing north had a gap or aperture of 1½ to 2 inches. Approximately four feet inside the unit, directly south of the curtain gap, was *589 a makeup table with a five foot mirror on it.

The officers parked their vehicles near unit 17 in a common parking area. In walking from his vehicle to the sidewalk area, Shilaos noticed a person, later identified as Herrera, looking out the door window and closely watching him. On reaching the sidewalk directly adjoining the unit, Shilaos noticed the gap or break in the curtains covering the window facing north. The room inside was well illuminated. From the sidewalk area he looked through this gap and observed a man, later identified as the defendant, seated at the makeup table in front of the large mirror inside the unit. Shilaos saw the defendant moving a pile of brownish granular material toward a larger pile of white powder and concluded that he was observing the cutting of heroin with milk sugar. He told Agent Shaw of his observations and immediately radioed for assistance.

Shilaos then ran to the front door of the unit, identified himself as a police officer, and demanded entry. Herrera held the door shut but Shilaos was able to push it open. As the officers entered the room the defendant was exiting the bathroom adjoining the bedroom and the toilet was flushing. Shilaos ran to the bathroom and saw a clear plastic bag containing the same brown granular material going down the toilet. He unsuccessfully attempted to retrieve the bag from the toilet. A brown powdery material was visible around the porcelain rim of the toilet and on some utensils in the bedroom. 2 On the makeup table in the bedroom were various implements associated with the dilution and use of heroin, including a bag of balloons, small measuring spoons, plastic lids, cotton swabs, a syringe, and an empty container of lactose.

The defendant and Herrera were placed under arrest and searched. Cash in the amount of $275 was recovered from the pants pocket of the defendant. With their hands and through the use of an adhesive tape, the officers gathered up 160 milligrams of material from the area under and around the makeup table. They also seized the narcotics paraphernalia plainly visible on the makeup table. The trial court denied the defendant’s pretrial motion to suppress the evidence recovered from the motel unit, concluding that Agent Shilaos’ initial observations of the defendant in the motel room were lawful and established probable cause and exigent circumstances to enter the motel unit for the purpose of arresting the defendant and seizing the evidence therein.

During the trial Officer Shilaos described the circumstances of the defendant’s arrest and the removal and preservation of the brown granules from the motel room. The granules were placed in a box and later were transmitted to the Colorado Bureau of Investigation (CBI) for chemical tests and then returned to the Lakewood Department of Public Safety. CBI Agent Netwall, whom the trial court received as an expert witness in analytical chemistry, testified that when he opened the box, there were no loose granules inside but, rather, all granules were sticking to the adhesive tape. The People offered into evidence the box and its contents, People’s Exhibit 10, to which the defendant objected on the ground that an unbroken chain of custody had not been sufficiently established. The court overruled the objection and admitted the exhibit.

Agent Netwall described various chemical tests performed on the residue recovered *590 from the motel and testified that in his opinion the 160 milligrams of material contained 21.6 milligrams of heroin. On cross-examination of Agent Netwall, defense counsel elicited testimony that 21.6 milligrams of heroin were the equivalent of 0.0007 of an ounce. On redirect examination Netwall testified that this amount represented a usable quantity of heroin and that other drugs, such as codeine, were used in amounts ranging from 2 to 15 milligrams. The defendant unsuccessfully objected to Netwall’s redirect testimony as beyond the qualifications of the witness and outside the scope of proper redirect examination.

During the prosecution’s case in chief the defendant unsuccessfully moved to strike the testimony of three prosecution witnesses on the grounds that they violated a sequestration order. Agent Knott, a member of the Lakewood Police Department, testified to the general method of illegal distribution and use of heroin. During a recess it was brought to the attention of the court that he had talked to Agent Shilaos about the condition in which Shilaos found the drug paraphernalia on the night of the arrest. The defendant moved for a mistrial and alternatively to strike Knott’s testimony and that of Shilaos. The prosecution argued that it intended to proffer this information to Agent Knott in the course of further direct examination by asking him a hypothetical question and, therefore, the defendant suffered no prejudice by the technical violation of the sequestration order. The trial court denied the defendant’s motion for a mistrial but ordered that there be no further direct examination of Agent Knott. It was also brought to the attention of the trial court that a conversation between the District Attorney and Agent Netwall about the percentages of active ingredients in certain drugs had been inadvertently overheard by Agent Knott. The defendant moved to strike the testimony of both Netwall and Knott. The trial court denied the motion to strike, finding that Knott’s overhearing the conversation was inadvertent.

At the conclusion of the People’s case the defendant moved unsuccessfully for a judgment of acquittal. Over the defendant’s objection the court included in the instructions the statutory definition of “sale” as including “barter, exchange, or gift, or offer therefor, and each such transaction made by any person, whether as principal, proprietor, agent, servant, or employee.” Section 12-22-301(25), C.R.S.1973 (1978 Repl. Vol. 5). The defendant tendered seven jury instructions, all of which were rejected. Two tendered instructions concerned the legal sufficiency and significance of evidence of useless traces of narcotics. Three of the defendant’s instructions related to the evidentiary significance of such matters as the recent past possession or use of narcotics, the mere presence of the defendant on premises where narcotics were found and the defendant’s joint possession of the motel room with another. The defendant’s other two instructions dealt with opinion testimony and the prosecution’s burden to prove that the amount of heroin actually recovered was usable.

The court submitted to the jury the crimes of possession of a narcotic drug, heroin, for sale with the intent to induce or aid another to use or possess the heroin, section 12-22-322(l)(a), C.R.S.1973 (1978 Repl. Vol. 5), and the lesser offense of possession of a narcotic drug, section 12 — 22— 302, C.R.S.1973 (1978 Repl. Vol. 5). The jury returned a verdict of guilty to the principal charge, resulting in a sentence to a term of seven to eight years, and this appeal followed.

II. The Seizure of Evidence

We first consider the defendant’s claim that the entry into the motel unit and the seizure of contraband and evidence therein constituted an unreasonable search and seizure in violation of the United States and Colorado Constitutions. U.S.Const. Amend. IV; Coio.Const. Art. II, Sec. 7. In challenging the trial court’s ruling denying the motion to suppress, the defendant argues three alternative propositions: (1) Agent Shilaos’ observations of the defendant through the curtains constituted a warrant- *591 less search and therefore they were invalid; (2) even if these observations were not a search, exigent circumstances did not exist for the warrantless entry into the motel room; and (3) even if exigent circumstances did exist, the subsequent warrantless search and seizure inside the motel unit were unconstitutional. We find the defendant’s arguments unpersuasive.

A.

In order for the exclusionary rule to apply, there first must be a determination that the challenged governmental conduct constitutes a search. Generally a search involves “some exploratory investigation, or an invasion and quest, a looking for or seeking out,” and “implies a prying into hidden places for that which is concealed ... . ” 1 W. LaFave, Search and Seizure § 2.1 at 222 (1978). Katz v. United States, 389 U.S. 347, 88 S.Ct. 507, 19 L.Ed.2d 576 (1967), provides the starting point for determining whether the officer’s initial observations of the defendant in the motel room constituted “a search” in the constitutional sense. In Katz the United States Supreme Court considered whether the governmental use of electronic equipment to overhear and record telephone conversations in a public telephone booth constituted a search and seizure. In rejecting traditional notions of trespass and constitutionally protected areas, the Court stated that “the Fourth Amendment protects people, not places,” id. at 351, 88 S.Ct. at 511, 19 L.Ed.2d at 582, and “the reach of that Amendment cannot turn upon the presence or absence of a physical intrusion into any given enclosure.” Id. at 353, 88 S.Ct. at 512, 19 L.Ed.2d at 583. The Court’s determination of the threshold question of search turned on whether the governmental activities “violated the privacy upon which [Katz] justifiably relied while using the phone booth ....” Id. at 353, 88 S.Ct. at 512, 19 L.Ed.2d at 583. While the Katz formulation of the scope of Fourth Amendment protections generally would consider “a man’s home . .. for most purposes [as] a place where he expects privacy,” nevertheless “objects, activities, or statements that he exposes to the ‘plain view’ of outsiders [would not be] ‘protected’ because no intention to keep them to himself has been exhibited.” Id. at 361, 88 S.Ct. at 516, 19 L.Ed.2d at 588 (Harlan, J. concurring). The appropriate question in this case thus becomes whether the defendant exhibited a reasonable expectation of privacy which was violated by an unjustified governmental intrusion into that privacy. See, e. g., People v. Becker, 188 Colo. 160, 533 P.2d 494 (1975).

The evidence at the suppression hearing does not yield the slightest suggestion that the police or anyone acting under their direction prearranged the curtains for the specific purpose of creating visual access to the interior of the motel unit. With no evidence of such governmental action, we do not believe the resolution of the search issue should depend on such fortuities as whether the gap was caused by a defective curtain rod, the occupant’s inadvertent arrangement of the curtains, or the normal hang of the curtains. See, e. g., People v. Berutko, 71 Cal.2d 84, 77 Cal.Rptr. 217, 453 P.2d 721 (1969). Here the evidence is undisputed that the observations were made by looking through a gap in the curtains from a sidewalk area used as a common entrance way to the defendant’s motel unit. Under such circumstances the defendant cannot claim a reasonable expectation of privacy from the intrusive glance of a passer-by:

“A sidewalk, pathway, common entrance or similar passageway offers an implied permission to the public to enter which necessarily negates any reasonable expectancy of privacy in regard to observations made there. The officer who walks upon such property so used by the public does not wear a blindfold; the property owner [or occupant] must reasonably expect him to observe all that is visible. In substance the owner [or occupant] has invited the public and officer to look and to see. But, by the same reasoning, the officer who intrudes upon property not so open to the public enjoys no such prerogatives.” Lorenzana v. Superi- *592 or Court of Los Angeles County, 9 Cal.3d 626, 629, 511 P.2d 33, 35, 108 Cal.Rptr. 585, 587 (1973).

Accordingly, we hold that where a police officer, while walking on a sidewalk used as a common entrance way to a motel unit, observes through a visual aperture in the window curtains the actions of the defendant occurring inside the motel unit, the observations of the officer do not constitute a “search” in the constitutional sense of that term and do not violate the Fourth Amendment to the United States Constitution or Article II, Section 7 of the Colorado Constitution.

B.

We proceed now to the question whether there was an exigency justifying the warrantless entry into the motel unit. The doctrine of exigent circumstances is limited to “those situations where, due to an emergency, the compelling need for immediate police action militates against the strict adherence to the warrant requirement.” McCall v. People, Colo., 623 P.2d 397, 402 (1981).

“Exigent circumstances justifying a warrantless arrest generally have been limited to those situations involving a bona fide pursuit of a fleeing suspect, e. g., Warden v. Hayden [387 U.S. 294, 87 S.Ct. 1642, 18 L.Ed.2d 782 (1967)]; United States v. Scott, 520 F.2d 697 (9th Cir. 1975), cert. denied, 423 U.S. 1056, 96 S.Ct. 788, 46 L.Ed.2d 645 (1976), or the risk of immediate destruction of evidence, e. g., United States v. Santana, 427 U.S. 38, 96 S.Ct. 2406, 49 L.Ed.2d 300 (1976); People v. Williams, Colo., 613 P.2d 879 (1980), or a colorable claim of emergency threatening the life or safety of another, e. g., People v. Amato, 193 Colo. 57, 562 P.2d 422 (1977). The scope of the doctrine, however, must be ‘strictly circumscribed by the exigencies which justify its initiation,’ Mincey v. Arizona, 437 U.S. 385, 393, 98 S.Ct. 2408, 2413, 57 L.Ed.2d 290, 300 (1978), quoting Terry v. Ohio, 392 U.S. [1], 25-26, 88 S.Ct. 1868, 1882, 20 L.Ed.2d 889, 908 (1968), and the burden is on the prosecution to establish that those exigencies render the warrantless entry truly imperative. E. g., Mincey v. Arizona, supra; Coolidge v. New Hampshire, 403 U.S. 443, 91 S.Ct. 2022, 29 L.Ed.2d 564 (1971); Warden v. Hayden, supra; Johnson v. United States, 333 U.S. 10, 68 S.Ct. 367, 92 L.Ed. 436 (1948).” Id. at -, 623 P.2d at 402.

The trial court’s finding of exigent circumstances is adequately supported by the record. Agent Shilaos was being watched from the motel unit by the defendant’s companion, Joseph Herrera, and Agent Shaw, who was in uniform, was readily visible from Herrera’s point of observation. It was apparent to Herrera and the defendant that the police were in the immediate vicinity of their motel room. When Shilaos observed the defendant’s illegal activity he was confronted with the urgent need to prevent the immediate destruction of the contraband. Time was of the essence and only an immediate entry into the motel unit could prevent the likely disposal of the contraband by the occupants. Even with instant entry, most of the contraband had already been flushed down the toilet.

C.

We next consider whether the officers legitimately seized the paraphernalia on the makeup table in the bedroom and the particles of granular material on the carpet under and around the makeup table, as well as the powdery material around the toilet rim in the bathroom.

“The scope of [a] search must be ‘strictly tied to and justified by’ the circumstances which rendered its initiation permissible.” Chimel v. California, 395 U.S. 752, 762, 89 S.Ct. 2034, 2039-40, 23 L.Ed.2d 685, 693 (1969), quoting Terry v. Ohio, 392 U.S. 1, 19, 88 S.Ct. 1868, 1878, 20 L.Ed.2d 889, 904 (1968). In this case the possible destruction of the very evidence seized was the basis for the initial entry into the motel unit.

Furthermore, the officers had probable cause to arrest the defendant inside the motel unit and that arrest furnished ample *593 justification for the seizure of the granular material and the narcotics paraphernalia. It is permissible for officers to search “the area ‘within [the defendant’s] immediate control’ — construing that phrase to mean the area from within which he might gain possession of ... destructible evidence.” Chimel v. California, supra, 395 U.S. at 763, 89 S.Ct. at 2040, 23 L.Ed.2d at 694; see also New York v. Belton, - U.S. -, 101 S.Ct. 2860, 69 L.Ed.2d 768 (1981). The small particles taken from the floor under and around the makeup table and from other areas in the unit could readily have been destroyed or lost if they were not seized on the spot. The other objects seized were connected with the crime and were within reach of the defendant and Herrera. Accordingly, the trial court did not err in denying the defendant’s motion to suppress the challenged evidence.

III. The Chain of Custody

The defendant contends that the prosecution failed to establish an unbroken chain of custody for People’s Exhibit 10, the box containing the particles of heroin lifted from the carpeting in the motel room. The defendant’s contention centers on a claimed discrepancy between Agent Shilaos’ testimony that he picked up some loose particles by hand and placed them in the box and Agent Netwall’s testimony that all the granules in the box adhered to the adhesive tape.

The defendant’s assertion notwithstanding, it is by no means clear that loose particles, unattached to the adhesive tape, ever found their way into the box. Agent Shil-aos testified that “I simply started picking up what I could with my fingers and placing them in a box and we were having difficulty in doing this ... so we tried using a piece of large scotch tape or transparent tape and pressfed] that against the carpet and pick[ed] some debris up that way . .. and we just placed that in the box.” But more importantly, the prosecution as proponent of the exhibit clearly established the chain of custody for the 21.6 milligrams of heroin recovered from the carpet, and the defendant presented no evidence indicative of tampering. “Where it is only speculation that there was tampering, it is proper to admit the evidence and let the jury determine its weight.” People v. Smith, 182 Colo. 228, 232, 512 P.2d 269, 271 (1973); accord, People v. Fite, Colo., 627 P.2d 761 (1981); People v. Atencio, 193 Colo. 184, 565 P.2d 921 (1977). We conclude that the trial court properly admitted the exhibit.

IV. Agent Netwall’s Redirect Examination

The defendant also challenges the trial court’s ruling permitting Agent Net-wall on redirect examination to testify that the 21.6 milligrams or 0.0007 ounces of heroin constituted a usable amount. The defendant argues that such testimony was beyond the qualifications of the witness and outside the scope of proper redirect examination. We find no error in the trial court’s ruling.

Without objection from the defendant the court permitted Agent Netwall to testify as an expert witness in analytical chemistry. Whether opinion testimony is within a witness’ expertise generally is a matter addressed to the sound discretion of the court and no abuse of discretion has been shown here. See, e. g., People v. Jiminez, 187 Colo. 97, 528 P.2d 913 (1974); Scott v. People, 166 Colo. 432, 444 P.2d 388 (1968); Starkey v. Bryan, 166 Colo. 43, 441 P.2d 314 (1968).

The defendant during his cross-examination of this witness inferentially injected into the trial the arguable issue of insufficient proof of guilty knowledge and/or possession due to the very minute amount of heroin recovered. Under these circumstances the trial court acted within its discretion in permitting the prosecution to question the witness about this matter “in an effort to dispel any unfavorable innuendo” created by the witness’ testimony on cross-examination. People v. Taggart, Colo., 621 P.2d 1375, 1386 (1981). See also, e. g., People v. Pickett, 194 Colo. 178, 571 P.2d 1078 (1977); Mathis v. People, 167 Colo. 504, 448 P.2d 633 (1968); Abeyta v. People, 156 Colo. 440, 400 P.2d 431 (1965).

*594 V.The Sequestration Order

We next consider whether the trial court erred in failing to grant a mistrial or, in the alternative, to strike the testimony of three prosecution witnesses because of their violation of the court’s sequestration order.

The trial court specifically found that although Agents Shilaos and Knott violated the sequestration order by discussing prospective testimony regarding heroin paraphernalia, that violation did not taint any prior or prospective testimony of these witnesses. The court, nevertheless, imposed the sanction of disallowing any further direct examination of Knott. Matters relating to the sequestration of witnesses and violations of sequestration orders traditionally have remained within the trial court’s sound discretion. E. g., Hampton v. People, 171 Colo. 153, 465 P.2d 394 (1970); Gomez v. People, 155 Colo. 507, 395 P.2d 462 (1964). We fail to perceive any abuse of discretion or, for that matter, any prejudice to the defendant by virtue of the limited sanction imposed by the trial court.

With respect to Agent Knott’s hearing a conversation between the deputy district attorney and Agent Netwall about the percentages of active ingredients in drugs, the court determined that this overhearing was inadvertent and no sanction would be appropriate. In this instance also we find no abuse of discretion.

VI.The Sufficiency of Evidence

Contrary to the defendant’s contention, we find the evidence sufficient to sustain his conviction. To withstand a motion for a judgment of acquittal the prosecution has the burden of presenting evidence which, when viewed as a whole and in a light most favorable to the prosecution, is substantial and sufficient to support a conclusion by a reasonable person that the defendant is guilty of a crime beyond a reasonable doubt. E. g., People v. Bennett, 183 Colo. 125, 515 P.2d 466 (1973). “The substantial evidence test affords the same status to circumstantial evidence as to direct evidence, and an exclusively circumstantial case need not exclude every reasonable hypothesis other than guilt to withstand a motion for a judgment of acquittal.” People v. Elkhatib, Colo., 632 P.2d 275, 279 (1981).

This is not a case where the prosecution’s evidence consists only of the discovery of a few particles of heroin, sprinkled on a carpet and a toilet rim in the defendant’s motel unit, with no additional evidence establishing his knowledge of its location and its character as a narcotic. See, e. g., People v. Theel, 180 Colo. 348, 505 P.2d 964 (1973); People v. Larsen, 180 Colo. 140, 503 P.2d 343 (1972); Ramsey v. People, 179 Colo. 172, 498 P.2d 1148 (1972). Although the amount of heroin admitted at trial was miniscule, there was ample testimonial and real evidence indicating that the defendant knowingly possessed a large amount of heroin but succeeded in preventing its seizure by flushing it away. The jury was not required to confine itself solely to the residue but rather could consider all the evidence, including the testimony depicting the defendant’s “cutting” a far greater quantity of heroin, his use of paraphernalia for this purpose, his destruction of most of the heroin moments before his arrest, and his possession of $275 in currency at the time of his arrest. When the evidence is appropriately viewed, it is sufficient to permit a reasonable person to conclude beyond a reasonable doubt that the substance in the defendant’s possession was heroin, that the defendant knew the heroin was in his possession, and that he possessed the heroin for the purpose of sale with the intent to induce or aid another to unlawfully use or possess the heroin. The trial court did not err in denying the defendant’s motion for a judgment of acquittal.

VII.Jury Instructions

The defendant argues that the court improperly instructed the jury that a sale “means barter, exchange, or gift, or offer therefor . ... ” Although he asserts that such definition violates due process of law, we find nothing in the definition which is unconstitutionally vague. It was within the legislative prerogative to include the aforementioned categories within the statu *595 tory definition of sale in section 12-22-301(25), C.R.S.1973 (1978 Repl. Vol. 5). See People v. Edwards, 198 Colo. 52, 598 P.2d 126 (1979). The court’s instruction merely repeated this statutory definition.

We proceed to consider the defendant’s claims regarding the trial court’s refusal of seven tendered jury instructions. One tendered instruction stated that “evidence of useless traces ... of narcotic substances does not constitute sufficient evidence to sustain a conviction .... ” Another instruction essentially repeated this same principle by stating that possession of useless traces likewise is insufficient to sustain a conviction. Although the court rejected these instructions in the form tendered, it did instruct the jury that “evidence of possession of useless traces or residues of narcotic substances, in and of itself, does not constitute sufficient evidence to sustain a conviction . . . . ” In view of the trial evidence from which the jury reasonably could conclude that the defendant knowingly possessed an amount of heroin far in excess of mere traces or residue, the court’s instruction correctly stated the principle of law applicable to this case and the defendant’s tendered instructions were properly refused. See, e. g., Romero v. People, 181 Colo. 305, 509 P.2d 301 (1973).

The defendant also tendered instructions dealing with the evidentiary significance of recent past possession or use of narcotics, his mere presence on premises where narcotics are found, and his joint possession of the motel room with another. The trial court did not err in refusing these instructions. They contain statements of law which are either incorrect or inapplicable to the facts of the case. The instructions actually given correctly outlined and defined the essential elements of the offenses submitted to the jury and included definitions of possession, knowledge and specific intent, and a clear statement of the prosecution’s burden to prove guilt beyond a reasonable doubt on all essential elements of a crime.

One of the defendant’s tendered instructions dealt with opinion testimony. The court properly instructed the jury on the opinion testimony of expert witnesses, Colo. J.I. (Grim.) 4:10, and the giving of the defendant’s tendered instruction on this matter would have been improper.

The last tendered instruction stated that the prosecution had the burden to prove beyond a reasonable doubt that the residue of heroin recovered from the motel unit was usable for consumption or sale. This instruction was misleading and therefore properly refused. The prosecution’s burden was to establish that the defendant knowingly possessed a usable amount of heroin for sale with the specific intent required by section 12-22-322(l)(a), C.R.S. 1973 (1978 Repl. Vol. 5). In determining whether the prosecution met its burden of proof, the jury was not required to confine itself to the residue itself but, rather, properly could consider all the evidence in the case.

The judgment is affirmed.