A jury found Mary Dangerfield Bengi-venga guilty of possessing marijuana with intent to distribute. A panel of this court reversed the conviction because the district court had denied Bengivenga’s motion to suppress evidence obtained before border patrol agents administered Miranda warnings.1 Our order granting rehearing en banc vacated the panel’s holding. We now affirm the conviction because Bengivenga was not “in custody” prior to her formal arrest and because, if a Miranda violation occurred, that alone would neither require exclusion of nontestimonial evidence nor trigger the derivative evidence rule.
I. FACTS
On February 1, 1986, shortly after midnight, Border Patrol Agents Santana and Ramos stopped a commercial bus at a fixed checkpoint located seven miles south of Falfurrias, Texas. Agent Santana boarded the bus at the secondary inspection point to conduct a routine citizenship check of the ten to fifteen passengers while Agent Ramos watched the exits. Two of the passengers, Bengivenga and a female companion, told Agent Santana that they were bound for Alice, Texas, a small town fifty miles north of the checkpoint.
After completing the citizenship check, Agent Santana left the bus to examine the luggage bins for illegal aliens. In the front compartment he detected a strong marijuana odor emanating from three similar suitcases. Agent Ramos confirmed this suspicion and the two agents removed the three suitcases from the luggage bin. The agents inspected the baggage claim tags and discovered that the suitcases were destined for Alice. Throughout this luggage inspection, the agents observed Ben-givenga and her companion peering nervously out the bus window.
Santana then informed Ramos that those two women were the only passengers who said they were traveling to Alice. Agent Ramos boarded the bus and first asked two men sitting in front of the women about their destination to determine whether they might be involved in smuggling the marijuana. When the men indicated that they were bound for San Antonio, Ramos proceeded to ask the women their destination and whether they had any luggage. They responded that they were bound for Alice and that they had not checked any luggage. Ramos then requested that they “please” step off the bus for further questioning. Ramos testified that further questioning is customarily done off the bus to avoid embarrassment to the suspect and to ensure the safety of the other passengers.
As they exited the bus, Ramos asked the women whether they owned the three suitcases. The women denied ownership. Ramos and Santana carried the luggage into the checkpoint trailer and requested the two women to accompany them. Agent Santana began filling out a baggage receipt form for the bus driver who was already in the trailer drinking coffee. In response to a question, the women again nervously denied that the suitcases belonged to them. Agent Ramos then requested the women to produce their bus tickets. When Bengivenga opened the envelope containing her ticket, Ramos noticed three baggage claim stubs which he asked to see. After matching the stubs to the baggage claim tags on the suitcases, Agent Ramos arrested the two women, advised them of their constitutional rights and opened the luggage. The agents found twenty-four kilograms of marijuana inside the suitcases.2 Approximately a minute *595and a half elapsed between the time the women entered the trailer and the time of their arrest.
Before her trial, Bengivenga moved to suppress her statements to the agents, her bus ticket, the baggage claim stubs and the marijuana arguing that she was “in custody” and entitled to Miranda warnings pri- or to being questioned in the trailer. Agent Eamos testified at the suppression hearing that he believed Bengivenga was free to refuse to accompany him to the trailer and he did not possess probable cause to arrest until he examined the baggage claim stubs. The district court denied the motion to suppress. At trial, the prosecution introduced the baggage claim stubs. Agent Eamos also testified at the trial that Bengivenga produced her bus ticket, that he observed baggage claim stubs in Bengi-venga’s ticket envelope and that he matched the stubs to baggage claim tags on the suitcases containing marijuana.
II. IN CUSTODY
Miranda warnings must be administered prior to “custodial interrogation.”3 The issue in this case is whether Bengivenga was “in custody” prior to producing her bus ticket and baggage claim stubs.
A. The Four Factor Test
This circuit has considered four factors on a case-by-case basis to determine whether a person is “in custody.” These factors are (1) whether there was probable cause to arrest the defendant, (2) whether the investigation was focused on the defendant at the time of interrogation, (3) whether the law enforcement officer had a subjective intent to hold the defendant, and (4) whether the defendant subjectively believed that her freedom was significantly restricted.4 Custody did not require the presence of all factors,5 but more than one factor had to be present.6
The district court held that Bengivenga was not in custody under this four factor test. First, the district court concluded that probable cause to arrest did not arise until after Bengivenga produced the baggage claim stubs and Agent Eamos matched them to the suitcases. Second, the district court found that the agents subjectively intended to restrict Bengiven-ga’s freedom of movement for only a limited and brief investigation of suspicious circumstances. Third, Bengivenga did not testify at the suppression hearing. The district court also found that the objective facts did not support an inference that Ben-givenga believed she was in custody. Finally, although the investigation had fo*596cused upon Bengivenga and her companion, the district court held that this factor alone was insufficient to render the interrogation custodial.
On appeal, the panel held that Bengiven-ga was in custody before being questioned in the trailer because the agents, in addition to having focused their investigation on the women, had probable cause to arrest. United States v. Bengivenga, 811 F.2d 853, 855 (5th Cir.1987). The panel, unlike this en banc court, was constrained by our past precedent. For the following reasons, we conclude that our four factor custody test is no longer compatible with Supreme Court precedent and must be abandoned in favor of the analysis we adopt today.
B. The Reasonable Person Test
The Miranda Court first defined “custodial interrogation” to “mean questioning initiated by law enforcement officers after a person has been taken into custody or otherwise deprived of his freedom of action in any significant way.”7 The meaning of custody has been refined so “the ultimate inquiry is simply whether there is a ‘formal arrest or restraint on freedom of movement’ of the degree associated with formal arrest.”8 The Supreme Court has also explained that “the only relevant inquiry is how a reasonable man in the suspect's position would have understood the situation.”9 A suspect is therefore “in custody” for Miranda purposes when placed under formal arrest or when a reasonable person in the suspect’s position would have understood the situation to constitute a restraint on freedom of movement of the degree which the law associates with formal arrest. The reasonable person through whom we view the situation must be neutral to the environment and to the purposes of the investigation — that is, neither guilty of criminal conduct and thus overly apprehensive nor insensitive to the seriousness of the circumstances.
1. Factoring out the Four Factor Test
Although the task of defining custody can be “a slippery one,”10 Supreme Court precedent has substantially undermined the four factors comprising our custody test. First, the existence of probable cause to arrest is largely immaterial to the question of custody. In a case holding that traffic stops do not ordinarily place a motorist in custody, the Court rejected the position that custody arises as soon as the level of suspicion amounts to probable cause to arrest. Berkemer v. McCarty, 468 U.S. 420, 435 n. 22, 104 S.Ct. 3138, 3148 n. 22, 82 L.Ed.2d 317 (1984).
The threat to a citizen’s Fifth Amendment rights that Miranda was designed to neutralize has little to do with the strength of an interrogating officer’s suspicions. And, by requiring a policeman conversing with a motorist constantly to monitor the information available to him to determine when it becomes sufficient to establish probable cause, the [proposed rule] would be extremely difficult to administer.
Id. Police officers are not required to effectuate an arrest the moment probable cause arises.11 Regardless of the presence *597of probable cause, until an officer acts to exert some type of restraint a suspect cannot reasonably believe her freedom is restrained.
The Supreme Court has also made it clear that focus alone does not create Miranda custody.12 Acknowledging this rule,13 our cases have held that custody arises when focus is coupled with another factor such as probable cause.14 Even this approach remains problematic because the exertion of restraint no more accompanies focus than it does probable cause. In particular, the presence of probable cause and focus often adds little to the custody equation because facts that establish these two factors tend to coalesce.15 Probable cause and focus become material to the custody inquiry only when they influence a reasonable person’s perception of the situation.16 To consider these factors in any other light may hamper legitimate police practices that do not threaten Fifth Amendment rights.
Finally, both our third and fourth factors —the unrevealed subjective intent of the law enforcement officer and the subjective belief of the suspect — are irrelevant to the custody determination. The Supreme Court recently stated that “[a] policeman’s unarticulated plan has no bearing on the question whether a suspect was ‘in custody’ at a particular time; the only relevant inquiry is how a reasonable man in the suspect’s position would have understood his situation.”17 Consideration of the subjective belief of the suspect may have an apparent logical soundness because “a person who honestly but unreasonably believes he is in custody is subject to the same coercive pressures” as one whose belief is reasonable.18 But the Supreme Court adopted a reasonable person test because it “ ‘is not solely dependent either on the self-serving declarations of the police officers or the defendant nor does it place upon the police the burden of anticipating the frailties or idiosyncracies of every person whom they question.’ ” 19
2. Miranda Custody and Fourth Amendment Seizures
In the past, we have questioned the relationship between Miranda custody and the Fourth Amendment’s proscription of unreasonable seizures. See, e.g., United States v. Brunson, 549 F.2d 348, 356 n. 9 (5th *598Cir.), cert. denied, 434 U.S. 842, 98 S.Ct. 140, 54 L.Ed.2d 107 (1977). We know that “a person has been ‘seized’ within the meaning of the Fourth Amendment only if, in view of all the circumstances surrounding the incident, a reasonable person would have believed that he was not free to leave.”20 But a Fourth Amendment seizure does not necessarily render a person in custody for purposes of Miranda. For example, traffic stops — stops which constitute a Fourth Amendment seizure21 — do not automatically place a person in custody for purposes of Miranda.22 In Brunson, 549 F.2d at 357 n. 12, a panel of this court noted that “the core meaning both of ‘seizure’ in the Fourth Amendment sense, and of ‘custody’ in the Miranda sense, appears to be the same: the restraint of a person’s ‘freedom to walk away’ from the police.” The critical difference between the two concepts, however, is that custody arises only if the restraint on freedom is a certain degree — the degree associated with formal arrest. .
C. Application of the Reasonable Person Test
A stop at a fixed checkpoint constitutes a Fourth Amendment seizure23 — a reasonable person would believe that she was not free to leave. Bengivenga was seized from the time that her bus was stopped at the checkpoint until her arrest, but her situation, as understood by a reasonable person, did not at any time prior to production of the baggage claim stubs involve a degree of restraint associated with formal arrest.
1. Routine Citizenship Cheeks at Fixed Checkpoints
Routine citizenship checks at fixed checkpoints are characterized by the same two features important to Berkemer’s holding that an ordinary traffic stop does not render a motorist in custody. First, traffic stops are “presumptively temporary and brief.” Berkemer, 468 U.S. at 437, 104 S.Ct. at 3149.
The vast majority of roadside detentions last only a few minutes. A motorist’s expectations, when he sees a policeman’s light flashing behind him, are that he will be obliged to spend a short period of time answering questions and waiting while the officer checks his license and registration, that he may then be given a citation, but that in the end he most likely will be allowed to continue on his way.
Id. Stationhouse interrogation, on the other hand, frequently may be prolonged and a reasonable person might expect questioning to continue “until he provides his interrogators the answers they seek.” Id. at 437-38, 104 S.Ct. at 3149. Second, traffic stops are less “police dominated” than sta-tionhouse interrogations. Id. at 438-39, 104 S.Ct. at 3149-50. The public nature of traffic stops reduces the hazard that police might resort to overbearing means to elicit incriminating responses and diminishes the motorist’s fear of abuse by the police if he fails to cooperate. Id. at 438, 104 S.Ct. at 3149. That no more than one or two police officers usually participate in a traffic stop also mitigates a motorist’s sense of vulnerability. Id.
A routine checkpoint stop involves “brief detention,” limited questioning and possibly production of a relevant document.24 The degree of restraint associated with arrest is more enduring and less circumspect. *599A fixed checkpoint mitigates the “subjective” fear a reasonable person might otherwise experience when their vehicle is stopped by border patrol agents. Id. at 558-59, 96 S.Ct. at 3083. Fixed checkpoints do not take travelers “by surprise as they know, or may obtain knowledge of, the location of checkpoints and will not be stopped elsewhere.” Id. at 559, 96 S.Ct. at 3083. The law enforcement presence at a fixed checkpoint actually assuages the reasonable person’s perception of restraint: “The regularized manner in which established checkpoints are operated is visible evidence, reassuring to law-abiding motorists, that the stops are duly authorized and believed to serve the public interest.” Id. Even for those travelers directed to secondary inspection points, “[t]he objective intrusion of the stop and inquiry ... remains minimal.” Id. at 560, 96 S.Ct. at 3084. Like a traffic stop, routine citizenship checks usually take place in the view of other travelers and are usually conducted by one or two officers. Routine citizenship checks at fixed checkpoints do not impose a degree of restraint associated with arrest because the detention is by nature brief and subject to the scrutiny of other travelers, the intrusion is limited in scope, advance notice obtains and visible signs of authority mitigate rather than enhance the perceived degree of restraint. Bengivenga therefore was not in custody at the time Agent Santana questioned her on the bus.
2. Investigation of Drug Smuggling
Once the agents discovered the suitcases suspected of containing marijuana, their activity shifted from a routine checkpoint stop aimed at detecting illegal aliens to an investigation of drug smuggling. That Bengivenga and her companion were the only passengers destined for the same town as the suitcases which smelled of marijuana coupled with their nervous behavior during the search of the luggage bins made them prime suspects. But the agents, believing that they did not possess probable cause, engaged in further conduct more analogous to a noncustodial investigative stop than a formal arrest.
Officers possessing reasonable articula-ble suspicion of a person’s participation in criminal activity may seize the suspect in accord with the Fourth Amendment to conduct an investigative stop — a narrow intrusion involving limited detention accompanied by brief questioning and, if justified, a frisk for weapons.25 Such investigative stops do not render a person in custody for purposes of Miranda. Berkemer, 468 U.S. at 439-40, 104 S.Ct. at 8150. When Agent Ramos boarded the bus and asked the two women their destination and whether they had any luggage, he was conducting a noncustodial investigation. The women’s answers did not completely allay his suspicion because they reconfirmed that their destination coincided with the destination of the luggage. Neither did the questions asked at this time exhaust the permissible scope of investigative questioning. In accord with a policy designed to assure the safety of the agents and the other passengers, Ramos requested the women to exit the bus. As in Berkemer, 468 U.S. at 441-42, 104 S.Ct. at 3151, where an officer asked a motorist to step out of his car and to perform a sobriety test, simply asking passengers to step off a bus and inquiring about ownership of luggage does not render a suspect in custody.
The agents then escorted Bengivenga and her companion to the nearby checkpoint trailer to continue the questioning. Several factors counteract the effect that moving a suspect from a bus to a building maintained by law enforcement personnel would ordinarily have on a reasonable person’s perception of the situation and the degree of restraint imposed. First, the trailer was only a short distance from the bus. Second, the conduct of the agents remained subject to the public scrutiny to the extent that the bus driver was actually present in the trailer drinking coffee. The agents did not completely isolate the women in an interrogation room. Third, the *600number of agents did not increase. Only five people were present in the trailer — the bus driver, the two women and the two agents. Changing the locus of the questioning to the trailer had the advantage of eliminating the potentially embarrassing presence of other bus passengers. With Agent Santana preoccupied with completing a baggage receipt form for the bus driver, it was unlikely that the agents might team up to overbear Bengivenga’s will.26 Finally, a reasonable person in Ben-givenga’s position would have understood that so long as the bus driver remained in the trailer the bus would not depart and if everything checked out she would shortly rejoin the other passengers on the bus.
Other than being moved to the nearby trailer, the objective facts do not indicate that the border agents imposed a degree of restraint associated with formal arrest. The agents did not communicate the basis for their suspicions. Their reluctance to assert restraint stemmed from their belief that they did not possess probable cause until after they matched the baggage claim stubs to the three suitcases. At no time during the minute and a half that elapsed in the trailer before formal arrest was Ben-givenga given any reason to believe that her detention would be other than temporary. Nor did the nature of the questioning intensify once inside the trailer. The incriminating baggage claim stubs inadvertently surfaced in response to a request to see Bengivenga’s bus ticket, a question likely to be routinely asked of any bus passenger who becomes the object of an investigative stop. Rather than successive confrontations with the border agents, Ben-givenga was subjected to no more than a routine citizenship check that quickly progressed from an investigative stop to her formal arrest. At no time prior to production of the baggage claim stubs did this situation, as understood by a neutral and reasonable person in Bengivenga’s position, involve the degree of restraint associated with formal arrest.
III. NONTESTIMONIAL EVIDENCE AND THE FRUIT OF THE POISONOUS TREE DOCTRINE
Assuming Bengivenga was in custody at the time of the interrogation in the trailer, we would affirm her conviction because a Miranda violation would not require suppression of the evidence introduced at her trial.
A. Nontestimonial Evidence
The privilege against self-incrimination “applies only when the accused is compelled to make a testimonial communication that is incriminating.” Fisher v. United States, 425 U.S. 391, 408, 96 S.Ct. 1569, 1579, 48 L.Ed.2d 39 (1976) (emphasis in original). This privilege ordinarily does not apply to nontestimonial evidence. See, e.g., Schmerber v. California, 384 U.S. 757, 764, 86 S.Ct. 1826, 1832, 16 L.Ed.2d 908 (1966) (suspect may be compelled to supply incriminating blood samples). A violation of Miranda rules, rules fashioned to secure the Fifth Amendment’s privilege during custodial interrogation,27 necessitates only the exclusion of testimonial evidence from the prosecution’s case in chief.28 The bus ticket and baggage claim stubs are nontestimonial physical evidence and would not be excludable even if they had been obtained in violation of Miranda.
Bengivenga also urges that her acts of producing the bus ticket and baggage claim stubs constitute statements for Miranda purposes. We hold, however, that Bengi-venga’s act of producing her bus ticket is not a statement for Miranda purposes. Every passenger on the bus must purchase a ticket. The implicit admission of the existence and possession of a bus ticket that accompanies the act of its production does not rise “to the level of testimony within the protection of the Fifth Amend*601ment” because existence and possession of a bus ticket are a “foregone conclusion.” Fisher, 425 U.S. at 411, 96 S.Ct. at 1581.
Whether the act of producing the baggage claim stubs could be a statement for Miranda purposes in some other context is beside the mark for the prosecution independently established the existence and possession of the stubs. As Bengivenga produced her bus ticket, an act we hold to be nontestimonial, Agent Ramos observed baggage claim stubs inside her ticket envelope. The fact that Bengivenga complied with the subsequent request by Agent Ramos to produce those stubs does not alter the nontestimonial nature of his observations. At trial, Agent Ramos testified only to the observations he made before Bengi-venga produced the baggage claim stubs and to the fact that he linked those stubs to the suitcases containing marijuana. The prosecution thereby established the existence of the stubs and their possession by Bengivenga without reference to how they were produced.
B. The Fruit of the Poisonous Tree Doctrine
Even nontestimonial evidence, according to Bengivenga, must be suppressed if it is tainted by custodial interrogation that occurs in violation of Miranda. This contention is contrary to the rule that a mere violation of Miranda’s “prophylactic” procedures does not trigger the fruit of the poisonous tree doctrine. The derivative evidence rule operates only when an actual constitutional violation occurs, as where a suspect confesses in response to coercion.29 None of the tactics employed by the agents were “so offensive to a civilized system of justice that they must be condemned.” Miller v. Fenton, 474 U.S. 104, 109, 106 S.Ct. 445, 449, 88 L.Ed.2d 405 (1985). Agent Ramos politely requested Bengivenga and her companion to accompany him to the nearby checkpoint trailer where they were questioned for about a minute and a half. Bengivenga remained resolute throughout her entire encounter with the agents; she never admitted ownership of the suitcases. None of the evidence introduced at Bengivenga’s trial should have been excluded under the derivative evidence rule because the record is simply barren of any evidence of coercion.30
IV. CONCLUSION
The agents were not required to administer Miranda warnings before questioning Bengivenga. At no point prior to production of the baggage claim stubs was she in custody. Even if Bengivenga was placed in custody upon entering the checkpoint trailer, the evidence introduced at trial should not have been suppressed because it was nontestimonial and the derivative evidence rule was not triggered by an actual constitutional violation. For these reasons, the conviction appealed from is
AFFIRMED.
. United States v. Bengivenga, 811 F.2d 853 (5th Cir.1987).
. The district court held that the warrantless search of the luggage did not contravene the Fourth Amendment because the Falfurrias checkpoint had been recognized as a functional equivalent of the border. See United States v. Salinas, 611 F.2d 128 (5th Cir.1980). Although this circuit has previously authorized plenary searches at such checkpoints, we recently re*595fused to uphold plenary searches at the Sierra Blanca fixed checkpoint on a functional equivalency of the border theory. United States v. Jackson, 825 F.2d 853, 860-62 (5th Cir.1987) (en banc), cert. denied sub nom. Ryan v. United States, — U.S. -, 108 S.Ct. 711, 98 L.Ed.2d 661, cert. denied sub nom. Browning v. United States, — U.S. -, 108 S.Ct. 730, 98 L.Ed.2d 679 (1988). In Jackson, we nonetheless declined to suppress any evidence because the deterrence rationale of the exclusionary rule would not be advanced where agents acted in good faith reliance on our prior precedent. Id. at 865-66. Without considering whether the search of Ben-givenga’s luggage might be justified on a theory other than functional equivalency, we simply note that the exclusionary rule would not apply to the marijuana because the agents conducted the search in good faith prior to our decision in Jackson. Id. at 866.
.Absent "other fully effective means,” a person subjected to custodial interrogation
must be warned prior to any questioning that he has the right to remain silent, that anything he says can be used against him in a court of law, that he has the right to the presence of an attorney, and that if he cannot afford an attorney one will be appointed for him prior to any questioning if he so desires.
Miranda v. Arizona, 384 U.S. 436, 479, 86 S.Ct. 1602, 1630, 16 L.Ed.2d 694 (1966).
. See, e.g., United States v. Warren, 578 F.2d 1058, 1071 (5th Cir.1978) (en banc), cert. denied, 446 U.S. 956, 100 S.Ct. 2928, 64 L.Ed.2d 815 (1980).
. See, e.g., United States v. Jordan, 557 F.2d 1081, 1083-84 (5th Cir.1977) (absence of probable cause does not preclude a finding of custody when the other three factors are present); Alberti v. Estelle, 524 F.2d 1265, 1267 (5th Cir.1975) (probable cause plus focus establish custody), cert. denied, 426 U.S. 954, 96 S.Ct. 3181, 40 L.Ed.2d 1193 (1976).
. See, e.g., Brown v. Beto, 468 F.2d 1284, 1286 (5th Cir.1972) ("none of those factors is alone determinative”).
. Miranda, 384 U.S. at 444, 86 S.Ct. at 1612 (footnote omitted); see also id. at 477, 478, 86 S.Ct. at 1629, 1630.
. California v. Beheler, 463 U.S. 1121, 1125, 103 S.Ct. 3517, 3520, 77 L.Ed.2d 1275 (1983) (per curiam) (quoting Oregon v. Mathiason, 429 U.S. 492, 495, 97 S.Ct. 711, 714, 50 L.Ed.2d 714 (1977) (per curiam)); see also Berkemer v. McCarty, 468 U.S. 420, 440, 104 S.Ct. 3138, 3150, 82 L.Ed.2d 317 (1984); Minnesota v. Murphy, 465 U.S. 420, 430-31, 104 S.Ct. 1136, 1144, 79 L.Ed.2d 409 (1984).
. Berkemer, 468 U.S. at 442, 104 S.Ct. at 3151 (footnote omitted).
. Oregon v. Elstad, 470 U.S. 298, 309, 105 S.Ct. 1285, 1293, 84 L.Ed.2d 222 (1985).
. There is no constitutional right to be arrested. The police are not required to guess at their peril the precise moment at which they have probable cause to arrest a suspect, risking a violation of the Fourth Amendment if they act too soon, and a violation of the Sixth Amendment if they wait too long. Law enforcement officers are under no constitutional duty to call a halt to a criminal investigation the moment they have the minimum evidence to establish probable cause, a quantum of evidence which may fall short of the amount necessary to support a criminal conviction. *597Hoffa v. United States, 385 U.S. 293, 310, 87 S.Ct. 408, 417, 17 L.Ed.2d 374 (1966) (footnote omitted).
. Murphy, 465 U.S. at 431, 104 S.Ct. at 1144 (“[t]he mere fact that an investigation has focused on a suspect does not trigger the need for Miranda warnings in noncustodial settings”); see also Beheler, 463 U.S. at 1124 & n. 2, 103 S.Ct. at 3519 & n. 2; Mathiason, 429 U.S. at 495, 97 S.Ct. at 714; Beckwith v. United States, 425 U.S. 341, 347, 96 S.Ct. 1612, 1616, 48 L.Ed.2d 1 (1976).
. United States v. Alvarado Garcia, 781 F.2d 422, 426 (5th Cir.1986).
. Alberti, 524 F.2d at 1267-68 (criticizing the focus-plus-probable-cause rule).
. The difficulty with the focus-plus-probable-cause rule is ipost apparent where undercover agents infiltrate drug rings or other criminal activity. In such circumstances, criminals frequently make incriminating statements in response to questions posed after an agent has probable cause and the investigation has focused on the suspect. We generally have held that such situations provide no basis to infer coercion. See, e.g., United States v. Marks, 603 F.2d 582, 584 (5th Cir.1979) (per curiam) (even if focus and probable cause existed, statements made to undercover agents "were uttered in a context completely free from coercion”), cert. denied, 444 U.S. 1018, 100 S.Ct. 673, 62 L.Ed.2d 649 (1980).
. The awareness of the person being questioned by an officer that he has become the “focal point” of the investigation, or that the police already have ample cause to arrest him, may well lead him to conclude, as a reasonable person, that he is not free to leave, that he has been significantly deprived of his freedom. ...
Kamisar, "Custodial Interrogation" Within the Meaning of Miranda, in Criminal Law and the Constitution 355, 371 (Inst. for Cont.Educ. 1968) (emphasis in original).
. Berkemer, 468 U.S. at 442, 104 S.Ct. at 3151 (footnote omitted); see also Murphy, 465 U.S. at 431, 104 S.Ct. at 1144 (the intent of a probation officer who questions a probationer is immaterial to the custody issue).
. Mathiason, 429 U.S. at 497 n. 1, 97 S.Ct. at 715 n. 1 (Marshall, J., dissenting).
. Berkemer, 468 U.S. at 442 n. 35, 104 S.Ct. at 3151 n. 35 (quoting People v. P., 21 N.Y.2d 1, 9-10, 233 N.E.2d 255, 260, 286 N.Y.S.2d 225, 232 (1967)).
. United States v. Mendenhall, 446 U.S. 544, 554, 100 S.Ct. 1870, 1877, 64 L.Ed.2d 497 (1980) (footnote omitted); see also INS v. Delgado, 466 U.S. 210, 215, 104 S.Ct. 1758, 1762, 80 L.Ed.2d 247 (1984).
. Delaware v. Prouse, 440 U.S. 648, 653, 99 S.Ct. 1391, 1396, 59 L.Ed.2d 660 (1979) ("stopping an automobile and detaining its occupants constitute a 'seizure' within the meaning of [the Fourth Amendment], even though the purpose of the stop is limited and the resulting detention quite brief’).
. Berkemer, 468 U.S. at 440, 104 S.Ct. at 3150.
. United States v. Martinez-Fuerte, 428 U.S. 543, 556, 96 S.Ct. 3074, 3082, 49 L.Ed.2d 1116 (1976).
. Id. 428 U.S. at 558, 96 S.Ct. at 3083. Government statistics indicate that "the average length of an investigation in the secondary inspection area [at the San Clemente checkpoint] is three to five minutes.” Id. at 546-47, 96 S.Ct. at 3078. Agent Ramos testified that citizenship checks on buses usually take "thirty seconds to five minutes,” depending on the number of passengers.
. See Terry v. Ohio, 392 U.S. 1, 30, 88 S.Ct. 1868, 1884-85, 20 L.Ed.2d 889 (1968), and its progeny.
. Compare Berkemer, 468 U.S. at 438 n. 27, 104 S.Ct. at 3149 n. 27.
. Miranda v. Arizona, 384 U.S. 436, 458, 86 S.Ct. 1602, 1619, 16 L.Ed.2d 694 (1966).
. See Oregon v. Elstad, 470 U.S. 298, 307, 105 S.Ct. 1285, 1292, 84 L.Ed.2d 222 (1985).
. See, e.g., Id. 470 U.S. at 305-309, 105 S.Ct. at 1291-93 (successive confessions); United States v. Cherry, 759 F.2d 1196, 1209 & n. 20 (5th Cir.1985) (derivative physical evidence).
. Compare Mincey v. Arizona, 437 U.S. 385, 98 S.Ct. 2408, 57 L.Ed.2d 290 (1978) (four hour interrogation of sedated defendant in an intensive-care unit elicited involuntary statements); Davis v. North Carolina, 384 U.S. 737, 86 S.Ct. 1761, 16 L.Ed.2d 895 (1966) (sixteen days of incommunicado interrogation and coercive tactics designed to undermine alibi elicited involuntary statements).