Task: songer_appnatpr

What follows is an opinion from a United States Court of Appeals.
Intervenors who participated as parties at the courts of appeals should be counted as either appellants or respondents when it can be determined whose position they supported. For example, if there were two plaintiffs who lost in district court, appealed, and were joined by four intervenors who also asked the court of appeals to reverse the district court, the number of appellants should be coded as six.
In some cases there is some confusion over who should be listed as the appellant and who as the respondent. This confusion is primarily the result of the presence of multiple docket numbers consolidated into a single appeal that is disposed of by a single opinion. Most frequently, this occurs when there are cross appeals and/or when one litigant sued (or was sued by) multiple litigants that were originally filed in district court as separate actions. The coding rule followed in such cases should be to go strictly by the designation provided in the title of the case. The first person listed in the title as the appellant should be coded as the appellant even if they subsequently appeared in a second docket number as the respondent and regardless of who was characterized as the appellant in the opinion.
To clarify the coding conventions, consider the following hypothetical case in which the US Justice Department sues a labor union to strike down a racially discriminatory seniority system and the corporation (siding with the position of its union) simultaneously sues the government to get an injunction to block enforcement of the relevant civil rights law. From a district court decision that consolidated the two suits and declared the seniority system illegal but refused to impose financial penalties on the union, the corporation appeals and the government and union file cross appeals from the decision in the suit brought by the government. Assume the case was listed in the Federal Reporter as follows:
United States of America,
Plaintiff, Appellant
v
International Brotherhood of Widget Workers,AFL-CIO
Defendant, Appellee.
International Brotherhood of Widget Workers,AFL-CIO
Defendants, Cross-appellants
v
United States of America.
Widgets, Inc. & Susan Kuersten Sheehan, President & Chairman
of the Board
Plaintiff, Appellants,
v
United States of America,
Defendant, Appellee.
This case should be coded as follows:Appellant = United States, Respondents = International Brotherhood of Widget Workers Widgets, Inc., Total number of appellants = 1, Number of appellants that fall into the category "the federal government, its agencies, and officials" = 1, Total number of respondents = 3, Number of respondents that fall into the category "private business and its executives" = 2, Number of respondents that fall into the category "groups and associations" = 1.
Note that if an individual is listed by name, but their appearance in the case is as a government official, then they should be counted as a government rather than as a private person. For example, in the case "Billy Jones & Alfredo Ruiz v Joe Smith" where Smith is a state prisoner who brought a civil rights suit against two of the wardens in the prison (Jones & Ruiz), the following values should be coded: number of appellants that fall into the category "natural persons" =0 and number that fall into the category "state governments, their agencies, and officials" =2. A similar logic should be applied to businesses and associations. Officers of a company or association whose role in the case is as a representative of their company or association should be coded as being a business or association rather than as a natural person. However, employees of a business or a government who are suing their employer should be coded as natural persons. Likewise, employees who are charged with criminal conduct for action that was contrary to the company policies should be considered natural persons.
If the title of a case listed a corporation by name and then listed the names of two individuals that the opinion indicated were top officers of the same corporation as the appellants, then the number of appellants should be coded as three and all three were coded as a business (with the identical detailed code). Similar logic should be applied when government officials or officers of an association were listed by name.
Your specific task is to determine the total number of appellants in the case that fall into the category "natural persons". If the total number cannot be determined (e.g., if the appellant is listed as "Smith, et. al." and the opinion does not specify who is included in the "et.al."), then answer 99.

OPINION OF THE COURT
BECKER, Circuit Judge.
This appeal from convictions on a seven-count indictment, charging both conspiracy and substantive counts of importation and possession of morphine with intent to distribute it, raises two overriding issues: (1) the sufficiency of evidence to support the conviction; and (2) whether certain evidence seized incident to the arrest of appellant Charles Nolan, upon which two counts of the indictment depend, must be suppressed because the federal marshals who made the arrest failed to abide by the statutory “knock and announce” requirement, 18 U.S.C. § 8109 (1976), that applies to an arrest of a person in his home. We have no difficulty in concluding that there was sufficient evidence to sustain the convictions. The suppression however presents a close and difficult (and largely unexplored) question of the contours of the exigent circumstances “escape” exception to § 3109. We hold that on the facts of this case the seizure of evidence was lawful. Consequently we affirm the judgment on all counts.
I. Factual and Procedural Background
In October 1978, appellant became a fugitive when he failed to turn himself in to parole authorities for violating parole; a bench warrant issued for his arrest on October 3,1978. On October 19, 1978, appellant applied for a passport in the name of Rocco Favorite; over the course of the next two years he used this and other fraudulently obtained passports to travel back and forth between Europe, India, and the United States.
In 1978 appellant began to sell morphine to Shipley Danko, whom he had met in 1971 through a mutual friend, James Flora. Danko subsequently became the Government’s chief witness. In May of 1979, following detailed instructions given to him by appellant, Danko obtained a passport in the name of Harry Usher, and traveled under that name to India with a friend, Silvio Ferea. There they purchased morphine, and returned to the United States with the morphine secreted in their rectal cavities. The events surrounding the May 1979 trip are the subject of Count III of the indictment, charging appellant with aiding and abetting the importation of morphine in violation of 21 U.S.C. § 952(a) (1976) and 18 U.S.C. § 2 (1976).
In October 1979, appellant, Danko and James Flora traveled together to India. Appellant and Danko travelled under false passports. In India appellant took Danko and Flora to Benares, where the three of them purchased morphine. They returned to the United States in November 1979 with the morphine concealed in sundry body cavities. Appellant spent one night at Danko’s apartment in Pittsburgh; the next day he left, saying that he was going to take his “stuff” to a person named George in McKeesport, Pennsylvania. On a prior occasion appellant had told Danko that George was to replace James Flora as appellant’s morphine distributor. These events form the basis of Counts IV and V, which charge appellant with importation of morphine and with possession of morphine with intent to distribute it, in violation of 21 U.S.C. §§ 952(a) and 841(a)(1) (1976), respectively, and 18 U.S.C. § 2.
In January 1980, Danko returned to India with a group of people to purchase morphine. While there he encountered appellant, who invited Danko’s party to join his own party to go to Benares to buy morphine. Danko declined, and they separated. Appellant traveled to India again in May, June, and August 1980. On September 9, 1980, after his return from this last trip, he was apprehended at a motel near Pittsburgh and arrested for the 1978 parole violation. Pursuant to appellant’s arrest, federal agents seized, inter alia, quantities of morphine and hashish; this evidence formed the basis of Counts VI and VII, charging appellant with possession with intent to distribute those two substances, in violation of 21 U.S.C. §§ 841(a)(1) and 844(a) (1976), and of 18 U.S.C. § 2 (Count VI only).
In addition to the substantive counts described above, appellant was also charged in Counts I and II with engaging in conspiracies from October 1978 to September 1980, with other named and unnamed co-conspirators, to import morphine and to possess morphine with intent to distribute it, in violation of 21 U.S.C. § 963 and § 846 (1976).
Following a three-day jury trial in October 1982, appellant was convicted on all counts and sentenced to concurrent 20-year sentences on each of Counts I through VI and a one-year concurrent sentence on Count VII, to be followed by a lifetime term of special parole, see 21 U.S.C. § 841(b) (1976 & Supp. IV 1980), on Counts III, IV, V and VI.
II. Sufficiency of the Evidence
A. The Aiding and Abetting Count
Count III charged appellant with aiding and abetting Danko and Silvio Ferea in the importation of morphine. The classic definition of aiding and abetting is found in Nye & Nissen v. United States, 336 U.S. 613, 619, 69 S.Ct. 766, 769-70, 93 L.Ed. 919 (1949):
In order to aid and abet another to commit a crime it is necessary that a defendant “in some sort associate himself with the venture, that he participate in it as something that he wishes to bring about, that he seek by his actions to make it succeed.” L. Hand, J., in United States v. Peoni, 2 Cir. 100 F.2d 401,402 [ (1938) ].
Four elements must be proved by the Government to make out a case of aiding and abetting: “[First,] the person who is being aided... must be intentionally committing a crime; second, the aider or abettor must know that the other is committing a crime; third, the aider or abettor must have the purpose to aid that other to commit the crime; and, finally, fourth, the aider must in fact render aid or assistance.” United States v. Interstate Engineering Corporation, 288 F.Supp. 402, 428 (D.N.H. 1967) (Wyzanski, C.J.); see United States v. Van Scoy, 654 F.2d 257 (3d Cir.), cert, denied, 454 U.S. 1126, 102 S.Ct. 977, 71 L.Ed.2d 114 (1981); United States v. Scalzitti, 578 F.2d 507 (3d Cir.1978); United States v. Cades, 495 F.2d 1166 (3d Cir.1974). The Government has adduced sufficient proof of each of these elements.
As to the first element, Danko admitted his intent to import morphine. As to the second, Danko’s testimony concerning appellant’s provision of the necessary information to him was certainly sufficient to establish appellant’s knowledge that Danko was, in the very near future, going to act upon the information. In particular, Danko testified that he had told appellant that he would like to go to India to obtain morphine, and that he could use the money he would make by importing it; this conversation occurred just after appellant had expressed a desire to stop making such trips.'Appellant thereupon instructed Danko that it would be necessary to obtain a passport in someone else’s name and explained to Danko the procedure for securing such a passport. Appellant further told Danko that, upon arriving in New Delhi, he should go to the Crown Hotel and contact certain Frenchmen living on the third floor, who would be able to arrange for Danko to purchase the morphine. Appellant also advised Danko that he should pay no more than 35 rupees per gram for the morphine. Finally, appellant told Danko that the safest way to carry the morphine back into the United States was in a body cavity and explained to him how to package the morphine for transport in this manner. The jury could reasonably infer from this evidence that appellant knew that Danko was going to commit the crime in question. It was therefore unnecessary for the Government to show that Danko had specifically informed appellant of his plans immediately before acting upon them.
The third element also has been satisfied: because Danko specifically expressed an interest in committing precisely the crime that appellant said he had grown weary of committing personally, a jury could easily infer that appellant intended to aid Danko in committing that crime by providing such detailed instructions. Further, the evidence of similar subsequent trips taken by Danko and appellant together would have allowed the jury reasonably to infer that appellant benefitted from Danko’s first trip because he gained thereby a new partner in his ventures. This conclusion in turn would reasonably allow the jury to find that appellant had a purpose to aid Danko in the commission of this particular crime. We have stated before that
Although generally proof showing one to be an aider and abettor relates to events occurring before the charged crime of the perpetrator, evidence of acts subsequent to commission of the crime is competent to prove common design, and is significant in evaluating the conduct prior to the commission of the offense of one charged as an aider and abettor.
Government of the Virgin Islands v. Navarro, 513 F.2d 11,15 (3d Cir.), cert. denied, 422 U.S. 1045, 95 S.Ct. 2662, 45 L.Ed.2d 698 (1975).
Finally, as to the fourth element, Danko testified that he followed appellant’s instructions to the letter on this initial importation trip. There is thus evidence that appellant did in fact aid Danko in the commission of the crime.
Contrary to appellant’s contention, therefore, we think there was ample evidence to support all of the elements required to show that appellant aided and abetted Danko in the importation of morphine in May or June of 1979.
B. The October-November 1979 Substantive Counts
Appellant challenges on several grounds the sufficiency of evidence as to Count IV, charging importation, and Count V, charging possession with intent to distribute, deriving from the October-November 1979 trip to India made by appellant, Danko, and James Flora.
First, appellant complains that no test was made on the substance allegedly imported to prove that it was a “controlled substance” within the meaning of 21 U.S.C. § 812 (1976 & Supp. V 1981); the identification of the substance as morphine was supported only by Danko’s testimony that it had been purchased in India, and by the testimony of Danko and Danko’s girlfriend, Linda Wojtkowski, that they had injected some of the substance and recognized it as morphine by its appearance and its effects on them. Appellant’s contention that the Government must introduce evidence of a chemical analysis of a substance in order to establish its composition is insupportable. See, e.g., United States v. Clark, 613 F.2d 391, 405-06 (2d Cir.1979), cert. denied, 449 U.S. 820, 101 S.Ct. 78, 66 L.Ed.2d 22 (1980); United States v. Quesada, 512 F.2d 1043, 1045 (5th Cir.), cert. denied, 423 U.S. 946, 96 S.Ct. 356, 46 L.Ed.2d 277 (1975); United States v. Lawson, 507 F.2d 433, 438-39 (7th Cir.1974), cert. denied, 420 U.S. 1004, 95 S.Ct. 1446,43 L.Ed.2d 762 (1975). The testimony.of Danko and Wojtkowski, both habitual users of morphine, that the substance in question was morphine is more than sufficient to present a jury question on this issue, and the jury could reasonably have concluded that the substance was morphine.
Appellant next argues that there was insufficient evidence of intent to distribute on Count V, because the quantity of morphine imported was consistent with appellant’s having imported the morphine solely for his personal use as an addict. However, the evidence established that appellant and his companions purchased 300 grams of morphine in India for $300 and that this quantity had a street value in the United States of $75,000 to $90,000. A potential profit of $75,000 to $90,000, even divided among the three purchasers, is sufficient to allow a jury to infer intent to distribute. See United States v. Davis, 582 F.2d 947, 952 (5th Cir.1978) (gross profit of $3,000 on $5,000 resale sufficient to allow jury to infer intent to distribute), cert, denied, 441 U.S. 962, 99 S.Ct. 2408, 60 L.Ed.2d 1067 (1979); United States v. Riggins, 563 F.2d 1264, 1266 (5th Cir.) (profit of $3,000 on $3500 resale sufficient), cert. denied, 439 U.S. 848, 99 S.Ct. 148, 58 L.Ed.2d 150 (1978). Moreover, Danko testified that appellant said he was taking his “stuff” to George in McKeesport, whom appellant had previously identified to Danko as appellant’s new morphine distributor. It was certainly reasonable for the jury to infer that the “stuff” appellant was taking to George was morphine to be sold. There was thus sufficient evidence both that the substance imported in November 1979 was morphine and that appellant intended to distribute that morphine to support the jury’s verdict.
C. The Conspiracy Counts
Appellant lastly challenges the sufficiency of evidence of conspiracy to import morphine and conspiracy to possess with intent to distribute it. Both conspiracies are alleged to have run from October 1978 through September 1980.
Largely through the testimony of Danko, the Government established the following facts supporting the conspiracy counts. Danko first met appellant through James Flora, another named co-conspirator. In 1978, at or before the time the conspiracy is alleged to have commenced, Danko began to buy morphine from appellant. Appellant told Danko that he had brought the morphine from India and that since 1973 he had been importing morphine and distributing it in Pennsylvania through James Flora. In May 1979, appellant, who had just returned from India, gave Danko detailed instructions how to buy morphine in India. Appellant and Flora had made a number of trips to India between the spring of 1979 and May 1980, during which period neither appellant nor Flora had any regular means of support. There was evidence to show that appellant, Flora, and Danko returned together to the United States from one such trip, in October 1979, with morphine. Appellant and Flora were again in India together in January 1980 for the purpose of purchasing morphine. Finally, soon after his return from India in September 1980, appellant contacted Flora.
We begin our discussion by noting that the essence of a conspiracy is an agreement, see United States v. Kates, 508 F.2d 308, 310 (3d Cir.1975), and that the Government may rely on circumstantial evidence of appellant’s involvement in the conspiracies alleged, rather than having to prove a formal agreement. See Hamling v. United States, 418 U.S. 87, 124, 94 S.Ct. 2887, 2911, 41 L.Ed.2d 590 (1974); Kates, supra. Moreover, the conspiracy statutes under which appellant was charged, 21 U.S.C. §§ 846 and 963, do not require proof of an overt act in furtherance of the conspiracy. See United States v. Dreyer, 533 F.2d 112, 117 n. 6 (3d Cir.1976). Finally, the Government need prove only that appellant conspired with at least one of the persons named in the indictment; failure to prove that all named co-conspirators conspired with appellant throughout the period alleged is not fatal to the Government’s case and is not in itself prejudicial to appellant. See United States v. Levine, 569 F.2d 1175, 1178 (1st Cir.), cert. denied, 436 U.S. 928, 98 S.Ct. 2824, 56 L.Ed.2d 771 (1978).
Under the applicable law, the evidence adduced at trial was sufficient to allow the jury to conclude that, from at least October 1978, appellant was engaged in an agreed-upon, ongoing venture with Flora to import and distribute morphine and that, in October 1979 at the latest, Danko also became a member of this conspiracy. Having found that, an agreement existed during this period, the jury could infer that the October 1979 trip formed a part of the agreed-upon scheme to distribute morphine. Appellant’s contentions are thus without merit; the overt acts proven were all relevant to showing a conspiracy and were, together with other evidence introduced by the Government, sufficient to show the existence of the conspiracies alleged in Counts I and II.
III. The Suppression Issue — Counts VI & VII
As we noted above, the officers who arrested appellant on September 9, 1980 seized morphine, hashish, various documents and drug paraphernalia from appellant’s motel room. Appellant does not challenge the sufficiency of the government’s evidence on Counts VI and VII; rather he (correctly) points out that if the evidence was unlawfully seized, the counts must fall. Appellant moved to suppress those items and any testimony by the officers concerning the items seized, on the grounds that the seizure was preceded and made possible by these officials’ entry into his motel room on two occasions without knocking on the door and announcing their identity and purpose, in violation of 18 U.S.C. § 3109.
A. Section 3109 and the Exigent Circumstances Exception: Basic Principles
As we have observed before, see United States v. Kane, 637 F.2d 974 (3d Cir.1981), section 3109 furthers three goals. First, it reduces the likelihood of injury to police officers, who might be “mistaken, upon an unannounced intrusion into a home, for someone with no right to be there.” Sabbath v. United States, 391 U.S. 585, 589, 88 S.Ct. 1755, 1758, 20 L.Ed.2d 828 (1968). Second, it seeks to prevent needless damage to private property. Finally, it embodies respect for the individual’s right of privacy, which is to be imposed upon as little as possible in making an entry to search or arrest. See Miller v. United States, 357 U.S. 301, 313, 78 S.Ct. 1190, 1197, 2 L.Ed.2d 1332 (1958).
The remedy for a violation of section 3109 is suppression of any evidence obtained as a result of the violation. See Sabbath, supra; Miller, supra; Kane, supra. This remedy is not expressly established by section 3109, but it has been judicially imposed in recognition of the shared common-law roots of that section and the fourth amendment. See generally Ker v. California, 374 U.S. 23, 47-52, 83 S.Ct. 1623, 1636-1639, 10 L.Ed.2d
726 (Brennan, J., concurring & dissenting); Miller, 357 U.S. at 306-10, 78 S.Ct. at 1194-96. Section 3109 has been interpreted to apply to breakings pursuant to arrest warrants as well as search warrants, see Miller, 357 U.S. at 306, 78 S.Ct. at 1194; Kane, 637 F.2d at 977. It has also been recognized, however, that certain exigent circumstances justify an unannounced entry to execute a warrant; evidence obtained under those circumstances will not be suppressed.
The statutory language itself provides one exception: it excuses preliminary notice “when [entry is] necessary to liberate [the officer] or person aiding him in the execution of the warrant.” In addition, we noted in Kane that the Supreme Court has apparently approved three other exceptions:
“(1) Where the persons within already know of the officers’ authority and purpose, or (2) where the officers are justified in the belief that persons within are in imminent peril of bodily harm, or (3) where those within, made aware of the presence of someone outside (because, for example, there has been a knock at the door) are then engaged in activity which justifies the officers in the belief that an escape or the destruction of evidence is being attempted.”
637 F.2d at 978, quoting Ker v. California, 374 U.S. 23, 47, 83 S.Ct. 1623, 1636, 10 L.Ed.2d 726 (1963) (Brennan, J., concurring & dissenting). To this list Kane added that “a police officer’s reasonable belief that announcement might place him or his associates in physical peril” would excuse compliance with the statute. Id. The Government contends that the unannounced entries in this case were justified by exigent circumstances. We therefore must determine whether the circumstances attending appellant’s arrest on September 9, 1980 fit within one of these exceptions.
B. The Events of September 9
On September 9,1980, an inspector and a deputy from the United States Marshal’s Office canvassed motels in Belle Vernon, Pennsylvania, acting on a tip from Danko that appellant might be staying in one of them. The marshals had in their possession the outstanding bench warrant that had been issued in October 1978 to arrest appellant for his parole violation. At about 2:00 P.M., they reached Motel 6, where the desk clerk recognized a photograph of appellant and told the marshals that appellant was registered in Room 48 under the name “Rocco Favorite.” The clerk also told them that “Mr. Favorite” had re-registered at 12:30 P.M. for an additional night and had apparently returned to his room. The two marshals went to the door of room 48, which was located near the rear exit on the ground floor of the motel. They observed that the rear exit of the motel let out into the parking lot. Listening at the door, they heard the sounds of a television or a radio.
The marshals then went back to the motel office to obtain a passkey. The manager returned with them to room 48, where the marshals had him knock on the door, say “manager,” and open the door. As the door opened, the marshals entered the room and simultaneously announced their identity. Appellant was not there, but the marshals noticed what looked like drug paraphernalia on a table. They withdrew after less than a minute without disturbing anything.
One marshal then watched the room while the other called for reinforcements. At 3:30 P.M. two more officers from the Marshal’s Office arrived, as did an agent from the Drug Enforcement Administration, and the five officers set up a stakeout to await appellant’s return. When appellant arrived, at about 4:45, two officers (apparently not in uniform) approached the door of his room as he walked towards it, in an attempt to apprehend him before he entered his room, but they arrived at the door after appellant had entered and locked it. Once again, the officers had the manager open the door and say “manager,” fearing that if they announced their identity and purpose, appellant would destroy the paraphernalia inside. The D.E.A. agent shouted “police” as the door opened. Appellant was subdued and arrested after a brief struggle, and the paraphernalia, a quantity of morphine, a quantity of hashish, and various identification papers were seized.
C. The District Court’s Resolution
The district court agreed with appellant that both entries had violated the terms of section 3109. In a careful opinion, the court first considered a number of preliminary questions and concluded (1) that section 3109 controls execution of an arrest warrant; (2) that a motel room is a “house” for purposes of section 3109; (3) that use of a passkey is a breaking within the meaning of section 3109; and (4) that the requirements of section 3109 were not avoided because the manager, at the officers’ behest, rather than the officers themselves, actually unlocked the door. 530 F.Supp. at 392-93. We endorse the court’s conclusions 'on these points and need not embellish on its reasoning here. The district court, however, denied appellant’s motion to suppress the evidence seized pursuant to the second entry, as well as the officers’ testimony concerning what they saw during both entries, holding that there were exigent circumstances justifying both the first and the second entries and that, in any event, the officers acted in good faith, thereby rendering inapplicable the sanction of exclusion.
The court found that the first entry was justified by the officers’ reasonable belief
(1) that [appellant] would be likely to try and escape; (2) that if he was in his room and tried to escape he would likely be successful in the short run because of the limited number of officers on the premises in relation to the potential number of exits and because of the relative proximity of the parking lot; and (3) if he was not in his room he would probably' see them waiting for him and escape; and (4) that if [appellant] escaped he would likely be successful in the long run through his use of aliases and transient living quarters and travel to foreign countries.
530 F.Supp. at 394. The belief was reasonable, the court found, in light of the officers’ knowledge (1) that appellant had avoided capture on his parole violation for two years, in part through his use of aliases, and (2) that the motel room had three potential exits, a door, and two windows.
The district court also found that the second entry was justified. Although fear of escape no longer provided an exigent circumstance justifying unannounced entry, the district court found justification on the basis of the officers’ reasonable belief that the objects they had seen during their first entry were nareotics-related paraphernalia, and that appellant, if he knew he was about to be arrested, would attempt to destroy those objects by flushing them down the toilet in the bathroom, which was in close proximity to the room in which the paraphernalia rested. Thus, the only exigent circumstance justifying the second entry was the fear that evidence would be destroyed, but the district court found this sufficient. Again, we find ourselves in complete agreement with the district court on this matter. Thus, the only point left for our resolution is the propriety of the first entry by federal law enforcement officials under the “escape exception” to section 3109, an issue to which we now turn.
D. The Contours of the Escape Exception
Prior judicial decisions have left the doctrinal contours of the “escape exception” to the knock and announce requirements of section 3109 charted only vaguely. To resolve the propriety of the first unannounced entry in this case a more precise map must be drawn.
We believe that a fair understanding of the purposes underlying section 3109 requires that law enforcement officials be able to invoke the “escape exception” to section 3109 only when they reasonably believe there is some likelihood that escape will be attempted and that escape will be successful. In making this determination, the likelihood of an attempt and the likelihood of success must be considered together. Where law enforcement reasonably believes the likelihood of an attempt to be strong, weaker evidence that an attempt would be successful will suffice to invoke the exception. Where the likelihood of an attempt is more remote, there must be stronger evidence known to law enforcement at the time that an attempt would be successful. Where both likelihoods are supported only weakly, officers must comply with the requirements of section 3109, unless, of course, another exception to that statute applies.
Our holding here obviously implies that federal law enforcement officials do not have to wait for reinforcements to arrive before executing an arrest warrant in order to prevent the “escape exception” to section 3109 from limiting the protective scope of that statute. If the federal officers have probable cause to believe a suspect named on an arrest warrant is inside a dwelling and if they reasonably believe there is some likelihood of escape if they knock and announce before entering, they may generally enter without complying with section 3109. Nor should courts assume that law enforcement can always significantly diminish the likelihood of successful escape by assigning one officer to each exit of a dwelling then occupied by the subject of an arrest warrant, or that the ability to cover each potential exit with an officer necessarily precludes the existence of exigent circumstances. Circumstances may well lead law enforcement reasonably to believe that such a spreading of strength would enable the suspect to escape, even when they do not believe that the spreading would subject them to a threat of violence sufficient to invoke the “dangerousness exception” to section 3109.
Although the issue is a close one, we do not think the district court clearly erred in finding that the federal law enforcement officials involved here could reasonably believe the likelihood of successful escape was high enough to warrant their dispensation with the knock and announce requirements of section 3109. First, the district court found that there was a likelihood of an attempt to escape. Although there may be some difference between simply failing to turn oneself in to a parole officer when told to do so and actively attempting to escape identified law enforcement officials knocking at one’s door, and although there was no specific evidence of propensity to escape, appellant was not the average criminal. He had been a fugitive for two years and had traveled to foreign countries under false passports and made use of numerous aliases throughout that time. Thus the district court’s finding was not clearly erroneous on this point.
Second, the district court found that, had there been an attempt, the police reasonably could have believed there to be a likelihood of success. If we accept the district court’s findings that the federal officers knew the number of exits to appellant’s motel room, there were.but two federal officers present at the time of the first entry. With two or possibly three exits to be covered, given the options an arrest strategy that must be left to the officers, see discussion supra, the finding that there was some likelihood that an escape attempt would be successful is not clearly erroneous. And when both factors are considered together, the evidence is sufficient to insulate the district court’s finding that exigent circumstances excused compliance with § 3109.
E. The Fourth Amendment Problem
If the prohibitions of section 3109 coincided perfectly with those of the fourth amendment bar on unreasonable searches, our inquiry would now be at an end. Having determined that the federal officials did not violate section 3109, we would also have determined that the fourth amendment had been satisfied. We believe, however, that the prohibitions of the two provisions overlap. Some conduct authorized by section 3109 may nonetheless violate the Constitution; conversely, some conduct permissible under the Constitution may be barred by section 3109. And, of course, some conduct may be unlawful under both provisions. Accordingly, after justifying our belief in the imperfect coincidence of section 3109 and the Constitution, we proceed to examine whether the search by federal officials in this case was constitutionally defective.
We begin by noting that the Supreme Court has never definitively determined the relationship between section 3109 and the Constitution. The Court’s opinions in Ker v. California, supra, and Miller v. United States, supra provide useful guidance, however.
In Miller, the Court discussed at some length the venerable common-law roots of the knock and announce requirement, and in concluding that a failure by federal law enforcement officers to announce their identity and purpose required suppression of the evidence seized, remarked:
The requirement of prior notice of authority and purpose before forcing entry into a home is deeply rooted in our heritage and should not be given grudging application. Congress, codifying a tradition embedded in Anglo-American law, has declared in § 3109 the reverence of the law for the individual’s right of privacy in his house.
357 U.S. at 313, 78 S.Ct. at 1198 (footnote omitted). The Court did not, however, expressly tie the knock and announce requirement to the fourth amendment’s proscriptions against general warrants and searches and seizures on less than probable cause.
In Ker v. California, supra, a plurality of four Justices concluded that state police had not violated the fourth amendment in breaking into an apartment to arrest the occupant without a warrant, and without first knocking and providing notice of their identity and purpose; the search incident to that arrest was therefore upheld. The plurality initially examined the lawfulness of the officers’ entry as a question of California law and concluded that, under state law, the unannounced entry was lawful. The plurality then addressed the question whether the state-law justification was sufficient to make the arrest “reasonable” under the fourth amendment. Finding Miller “inapposite for state prosecutions, where admissibility is governed by constitutional standards,” 374 U.S. at 39, 83 S.Ct. at 1633, the plurality held that “in the particular circumstances of this case the officers’ method of entry, sanctioned by the law of California, was not unreasonable under the standards of the Fourth Amendment as applied to the states through the Fourteenth Amendment.” Id at 40-41, 83 S.Ct. at 

Question: What is the total number of appellants in the case that fall into the category "natural persons"? Answer with a number.
Answer:

Answer: 1