LEVIN H. CAMPBELL, Chief Judge.
This case was previously before us when the government appealed from an order of the United States District Court for the District of Maine suppressing certain statements and physical evidence seized in connection with the arrest of defendant-appel-lee, Daniel Quinn, and a co-defendant, Thomas Streifel. The detailed facts are found in that opinion. United States v. Streifel, 781 F.2d 953, 954-57 (1st Cir. 1986). A summary will suffice for present purposes.
In March of 1984, a reliable informant told investigators from the Drug Enforcement Administration that a house in Naples, Maine, later found to be rented to one Cushner, was used as a “stash house” to store marijuana and that the persons involved used rented cars to transport the controlled substance. As a result of the informant’s communications, agents followed a vehicle driven by one Sterner to the Cushner house. After Sterner’s car left the house, they stopped and searched it, finding five bales of marijuana in the trunk.
Afterwards, on the same day, DEA agents commenced preparations to get a warrant to search the Cushner house. Pending issuance of the warrant, five officers, and a dog trained to identify marijuana by smell, went to the Cushner premises to “secure” them. Shortly after the five arrived, two of them, Steadman and Holmes, temporarily left to make a phone call that would give agents in Portland more information to be included in the search warrant. While the two officers were absent, two cars drove into the plowed Cushner driveway at about 10:45 in the evening. The first car, driven by Strei-fel, pulled in back of one of the agents’ cars, and the other car, driven by appellee Quinn, parked behind the Streifel car. Streifel and Quinn were asked by a uniformed officer for identification and to explain why they were at the cottage. Strei-fel produced his license and a rental agreement for his car while Quinn produced a car registration in his name. By way of explanation for their presence, Quinn replied that he was following Streifel to the house, as Quinn had been interested in renting it for the summer. Quinn and Streifel were told that they could not leave until the two absent officers returned.
At about 10:50 these two, Steadman and Holmes, arrived. They parked their car in back of Quinn’s car. There is a dispute as to whether after this action Quinn could have moved his car from the driveway. Appellee says he could not. The govern[155]*155ment says he could and cites to the transcript to support its contention that in fact other cars had done so. Agent Steadman asked both Quinn and Streifel what they were doing there, and they repeated that they had come to look at the cottage because Quinn was interested in renting it. Quinn and Streifel gave conflicting answers to questions about how they had met and how long they had known each other.
At approximately 11:10 the dog was instructed to “find the dope,” and it stopped at the trunk of Quinn’s car, reacting positively. Quinn was asked for permission to search the car, and he granted it, opening the trunk himself. The dog jumped inside and began digging at the floormat. The agent in charge of the dog then observed marijuana seeds and coffee grounds. Removing a blanket from where the dog was digging, the officer smelled marijuana remains. Quinn then asked that the dog be removed and the officer complied. Cush-ner himself then arrived, and Agent Stead-man asked him several questions including his relation to the house and whether he knew Quinn and Streifel. At this point, at about 11:25 p.m., Cushner and Quinn were given Miranda warnings. After a few more questions Agent Steadman and another officer accompanied Cushner inside the house. They found a plastic bag containing marijuana lying on a bureau. At approximately 11:45 p.m., Cushner, Quinn, and Streifel were arrested.
When this case was first before us, we determined that at least the initial questioning and detention of Streifel and Quinn at the scene had been a lawful Terry stop. Streifel, 781 F.2d at 959. We vacated and remanded for the district court to decide when, if ever, “the Terry stop of Streifel and Quinn matured into custodial interrogation necessitating the administration of Miranda warnings.” Id. at 960. We said that “[i]f the district court determines that Streifel and Quinn were placed in custody within the meaning of Miranda before they were advised of their rights, it may order suppressed any statements elicited in violation of Miranda, and, in light of its order, it should also make such rulings concerning the suppression of other evidence as it deems appropriate.” Id. at 962.
No further evidence was taken on remand. Relying on the original record, the district court arrived at essentially the same determination as before, finding that a de facto arrest without probable cause had occurred at the time Agents Steadman and Holmes “returned to the Cushner cottage and parked their cruiser in such a manner that neither defendants’ car could be moved from the driveway.” According to the court, the officers “affirmatively chose to block defendant in.” The court likened the situation to a “stationhouse interrogation,” turning a brief and temporary stop “into one fraught with pressure for defendants Quinn and Streifel.” Therefore, it suppressed the statements made by Quinn to Steadman without Miranda warnings and all the materials obtained from Quinn’s automobile, as the fruits of an illegal arrest.
In selecting the purported blocking of defendants’ car as the incident converting a Terry stop into an arrest, the district court explained that this event “in the total context then existing, was a determining factor tipping the balance in favor” of an arrest finding. The "total context,” as elsewhere discussed by the court, was that there were as many as five policemen and a police dog at the scene, defendants’ identification was not returned to them, they were kept apart while being questioned, and their interrogation was not done in a public place but in a remote cottage late at night. While there was no physical contact between the officers and defendants, no display of weapons, and no statements at this time indicating an arrest, the court concluded that an atmosphere was created threatening and coercive enough to warrant — indeed to require — the administration of Miranda warnings. The court also found that, since the agents lacked probable cause when the de facto arrest occurred, they could not use the fact that the dog later alerted to Quinn’s car as justification for the search of the automobile’s trunk. The court believed that Quinn’s consent to the search of the trunk of his automobile was a result of the atmosphere [156]*156of police domination followed by the dog’s sniff, a situation made possible only by the illegal detention. In summary, the court ordered the suppression of every kind of evidence gathered after Agent Steadman arrived at the scene. 683 F.Supp. 535.
Contrary to the court below, we believe that the actions of the police in the 20-25 minutes that transpired from the time Agents Steadman and Holmes returned until the dog sniff revealed the presence of marijuana, amounted to a reasonable continuation of the initial Terry stop in a “swiftly developing situation.” See United States v. Sharpe, 470 U.S. 675, 105 S.Ct. 1568, 1575-76, 84 L.Ed.2d 605 (1985). The only new factors that occurred after what we previously determined was a lawful Terry stop, were Steadman’s parking of his car behind Quinn’s car and the addition of Steadman and his companion to the three officers already present. All the other circumstances that the district court men-. tioned as the “context” within which the two new agents arrived, were present during the situation we earlier ruled was a lawful Terry stop. Thus the only question is whether the blocking of the car, the augmentation of the police presence by two more officers and the continuance of the inquiry, transformed the original Terry stop into either a de facto arrest or (if any different) a situation imposing “restraints comparable to those of a formal arrest.” Berkemer v. McCarty, 468 U.S. 420, 441, 104 S.Ct. 3138, 3151, 82 L.Ed.2d 317 (1984).
I. THE ADDITIONAL EVENTS DID NOT CHANGE THE TERRY STOP INTO AN ARREST.
The Supreme Court has said that “the exception for limited intrusions that may be justified by special law enforcement interests is not confined to the momentary, on-the-street detention accompanied by a frisk for weapons involved in Terry and Adams [v. Williams, 407 U.S. 143, 92 S.Ct. 1921, 32 L.Ed.2d 612 (1972)].” Michigan v. Summers, 452 U.S. 692, 700, 101 S.Ct. 2587, 2593, 69 L.Ed.2d 340 (1981). The Terry exception to the traditional rule disallowing detentions without probable cause has been widened in the last decade to encompass other circumstances where officers may make brief investigative stops or seizures of individuals upon reasonable suspicion that they may have committed, are committing, or are about to commit a crime. No mechanical checklist has been assembled to facilitate distinguishing between such investigative stops, on the one hand, and those detentions, on the other, which though not technical, formal arrests are the “equivalent of an arrest” and therefore require probable cause. People v. Hicks, 68 N.Y.2d 234, 508 N.Y.S.2d 163, 500 N.E.2d 861 (1986). Rather the cases have used a balancing test to assess these intrusions, weighing “the limited violation of the individual’s privacy against the opposing interests in crime prevention and detection and in the police officer’s safety.” Dunaway v. New York, 442 U.S. 200, 209, 99 S.Ct. 2248, 2254, 60 L.Ed.2d 824 (1979). In the present case, we think the actions of the police prior to the time they formally arrested Streifel and Quinn did not go beyond an investigatory Terry stop and did not amount to an arrest.
The district court attached great weight to the parking of Steadman’s cruiser behind Quinn’s vehicle. We may assume this made it harder, perhaps even impossible, for Quinn and Streifel to leave without the police’s moving Steadman’s car. Yet, as we said previously, “while the blocking of a vehicle is relevant to the issue of custody, it would not necessarily elevate an investigatory stop into a de facto arrest requiring probable cause.” Streifel, 781 F.2d at 961 n. 15. Based on the uncontested facts of the present case, we do,not believe this manner of parking was indicative of arrest-like restraint. The three cars that had preceded Steadman were all similarly lined up, one behind the other, in the plowed driveway. At the head of the line was the cruiser occupied by the first officers to arrive. Behind them was Streifel’s rented car, and behind Streifel’s was Quinn’s vehicle. Given that each one of these vehicles was parked directly behind the other, we can only infer that this mode of parking was a normal incident of the layout of the driveway and premises, sig-[157]*157nailing no special “custodial” designs by the owner of the rearmost car. In any case, a policeman’s subjective “unarticulated plan” has no significance for these purposes. Cf. Berkemer v. McCarty, 468 U.S. at 442, 104 S.Ct. at 3151. The relevant inquiry, as the Court has said, “is how a reasonable man in the suspect’s position would have understood his situation.” Id.1 We do not believe such a reasonable man, in Quinn’s shoes, would have thought that Steadman’s leaving of his car behind Quinn’s was tantamount to placing him under arrest.2
Similarly, we do not believe the physical presence of two more officers, besides the three who were there when the two suspects first arrived, could have led to a reasonable inference that a de facto arrest had occurred. Steadman and Holmes made no threats, displayed no weapons, and exerted no physical restraint upon Quinn’s person. While their arrival may have underscored the seriousness of the investigation, we do not think it would have sig-nalled to a reasonable person, standing in Quinn’s shoes, that he was under arrest.
Nor did the continued questioning of Streifel and Quinn after Steadman’s arrival convert the hitherto lawful Terry stop into an arrest. We ruled in our earlier opinion that detaining the suspects for Agent Steadman’s return was consistent with a Terry stop. Once Steadman arrived, it would be illogical to deny him an opportunity to confirm or dispel the suspicions that had justified the investigative stop in the first place. Checking out a suspicious person is a principal justification for an investigative stop. See Adams v. Williams, 407 U.S. 143, 146, 92 S.Ct. 1921, 1923, 32 L.Ed.2d 612 (1972) (“[a] brief stop of a suspicious individual in order to determine his identity or to maintain the status quo momentarily while obtaining more information, may be most reasonable in light of the facts known to the officer at the time”); United States v. Hensley, 469 U.S. 221,105 S.Ct. 675, 684, 83 L.Ed.2d 604 (1985) (reasonable suspicion justifies a brief detention at the scene of a stop while officers check whether a warrant against the suspects has in fact been issued).
A more difficult question is whether the 20-25 minutes from the time of the two agents’ arrival up to the dog’s alerting to the presence of drugs in the trunk of Quinn’s car was an excessive period of time to continue to interrogate the suspects. Compare United States v. West, 731 F.2d 90 (1st Cir.1984) (upholding airport stop involving somewhat comparable lapse of time before dog sniff of luggage). United States v. Davies, 768 F.2d 893, 902 (7th Cir.1985) (a 45-minute detention by two agents “for further questioning and advice from their superiors” held a valid investigative stop). “[T]here is no talismanic time beyond which any stop initially justified on the basis of Terry becomes an unreasonable seizure under the fourth amendment.” Id. at 901. In Sharpe, where detentions took place for periods somewhat comparable to that here, the Supreme Court reiterated its unwillingness to draw a “bright line” in respect to the duration of a Terry stop. 105 S.Ct. at 1575. Stating that “common sense and ordinary human experience must govern over rigid criteria,” the Court quoted with approval its early statement that, in investigating possible crimi[158]*158nal activity, “the police must under some circumstances be able to detain the individual for longer than the brief period in Terry ____” Id. The Sharpe Court went on to state, “[i]n assessing whether a detention is too long in duration to be justified as an administrative stop,” it is,
appropriate to examine whether the police diligently pursued a means of investigation that was likely to confirm or dispel their suspicions quickly, during which time it was necessary to detain the de-fendant____ A court making this assessment should take care to consider whether the police are acting in a swiftly developing situation, and in such cases the court should not indulge in unrealistic second-guessing.
Here, we see no way that the agents could have greatly shortened their inquiry if they were to “confirm or dispel their suspicions” meaningfully. The level of reasonable suspicion was such as to warrant a thorough, rather than a cursory, check. Compare United States v. Jodoin, 672 F.2d 232, 235 (1st Cir.1982) (longer detention of suitcase justified where there was cause for reasonable belief that suitcase contained drugs). Perhaps if Steadman had had only very weak grounds for suspicion, he should, as the court below suggested, have dismissed Quinn and Streifel after one or two questions. But Steadman had not only reasonable grounds, he had very strong grounds, approaching probable cause, for suspicion.3 We believe it would have been unreasonable to have sent Quinn and Streifel on their way after a few perfunctory questions, especially as the two suspects’ divergent answers as to how they had met raised rather than lowered the level of suspicion, inviting further inquiry. We conclude that Steadman and his associates did no more than “diligently pursue a means of investigation that was likely to confirm or dispel [his] suspicions quickly.”
We think, moreover, that a reasonable man would have believed only that he was being detained for investigation, not placed under arrest. Berkemer v. McCarty, 468 U.S. at 442, 104 S.Ct. at 3151. Except for being directed to await Steadman’s arrival, Quinn and Streifel were not told to stay nor advised they were in custody, nor were they physically threatened or held.
The district court felt that the lateness of the hour and the loneliness of the meeting place added to the suspects’ sense of helplessness. Yet it must be remembered that Streifel and Quinn had freely elected to come to the Cushner house; the location and the time of night were entirely of their own, not the officers’, choosing. Compare People v. Hicks, 68 N.Y.2d 234, 508 N.Y. S.2d 163, 500 N.E.2d 861 (1986) (police transported suspect in a cruiser to scene of the crime for possible identification by eyewitnesses; upheld as investigative stop); United States v. Betancur-Bustamonte, 799 F.2d 1388 (9th Cir.1986) (detention of over half an hour held justified as an investigative stop even when individual at airport was asked to accompany two agents on foot to an office approximately 100 yards away from the point of initial contact, passing on the way through two sets of locked doors). The failure of the officers to return Streifel’s and Quinn’s identification immediately, and the fact that use of a telephone may have been denied to Streifel (although the evidence on this latter point is scarcely clear, Streifel, 781 F.2d at 958 n. 9) are likewise insufficient, taken with all the other facts, to establish an arrest rather than an investigative stop. [159]*159Quinn’s conduct, we add, did not suggest he was intimidated. When Corporal Hutto asked for permission to search Quinn’s car, Quinn refused, and Hutto took no further steps at the time. Quinn also declined to answer one of Agent Steadman’s questions. When Quinn opened the trunk and the dog jumped in, he asked that the dog be removed.
Use of the dog was not itself improper. To be entitled to use a dog for purposes of making a sniff test, the officers were required merely to have had “reasonable suspicion” that the car contained narcotics, at the moment it was performed. United States v. Place, 462 U.S. 696, 698, 103 S.Ct. 2637, 2639, 77 L.Ed.2d 110 (1983). This standard, as noted, was plainly met.
Summarizing, the conduct by the officers in this case met the double approach adopted in Terry in that the “action was justifiable in its inception,” and it was “reasonably related in scope to the circumstances which justified the interference in the first place.” United States v. Sharpe, 470 U.S. 675, 105 S.Ct. 1568, 1573, 84 L.Ed.2d 605 (1985). Because of the information they already had, the officers had strong reason from the beginning to suspect the two late-hour arrivals at the Cushner house. The action they took with Quinn and Streifel was reasonable in that they just tried to gather more information to determine whether these individuals were involved in the crimes they were investigating. It was not unreasonable to keep defendants at the scene until Agent Stead-man, who was in charge of the operation, arrived and tried to find out the connections, if any, these individuals had with the narcotics contraband. See United States v. Kapperman, 764 F.2d at 792 (police acted diligently when they detained individual long enough to enable one of the officers in charge of the investigation to reach the scene and explain to the individual why he was being detained). The course of action Agent Steadman pursued was one “reasonably related in scope to the circumstances which justified the interference in the first place.” He tried to ascertain whether defendants were involved or not in the illegal actions. “[T]he right to interrogate during a ‘stop’ is the essence of Terry and its progeny.” United States v. Oates, 560 F.2d 45, 63 (2d Cir.1977). No display of force took place, and there is no evidence in the record of harassment or improper conduct by the officers. The situation was not such that a reasonable man would have thought he was under arrest. Thus, “[t]he nature and extent of the detention [were] minimally instrusive of the individual’s Fourth Amendment interests,” Place, 462 U.S. at 703, thereby supporting the detention on less than probable cause. The period of time that elapsed from the moment defendants arrived at the house to the moment that probable cause arose after the dog alerted to the presence of drugs in Quinn’s car, 25 minutes, was not unnecessarily long in these circumstances, especially as circumstances occurred within that period increasing the level of justified suspicion. The Supreme Court has stated:
Admittedly, Terry, Dunaway, Royer, and Place, considered together, may in some instances create difficult line-drawing problems in distinguishing an investigative stop from a de facto arrest. Obviously, if an investigative stop continues indefinitely, at some point it can no longer be justified as an investigative stop. But our cases impose no rigid time limitation on Terry stops. While it is clear that “the brevity of the invasion of the individual’s Fourth Amendment interests is an important factor in determining whether the seizure is so minimally intrusive as to be justifiable on reasonable suspicion,” ... we have emphasized the need to consider the law enforcement purposes to be served by the stop as well as the time reasonably needed to effectuate those purposes.
United States v. Sharpe, 105 S.Ct. at 1575.
Once the dog had alerted to a controlled substance, there was plainly probable cause to believe there were controlled substances in the car. Adams v. Williams, 407 U.S. at 148, 92 S.Ct. at 1924. Thus, the ensuing search of the vehicle was based on probable cause and was lawful. Carroll v. United States, 267 U.S. 132, 45 [160]*160S.Ct. 280, 69 L.Ed. 543 (1925); Chambers v. Maroney, 399 U.S. 42, 90 S.Ct. 1975, 26 L.Ed.2d 419 (1970). The search of the trunk revealed coffee grounds, marijuana seeds, and a blanket in which Agent Gallagher smelled marijuana. Pursuant to this and the other evidence defendants, including appellee, were lawfully arrested.
II. THE TERRY STOP WAS NOT ACCOMPANIED BY “RESTRAINTS COMPARABLE TO A FORMAL ARREST.”
Having held that the detention was a proper investigative stop, not a de facto arrest, we now inquire whether the nature of the detention, even though a Terry stop, involved “restraints comparable to a formal arrest” and so necessitated Miranda warnings. Streifel, 781 F.2d at 959-60; Ber-kemer v. McCarty, 468 U.S. at 441, 104 S.Ct. at 3151. The district court evidently felt that the presence of up to five officers and a dog, the loneliness of the site, the blocking of the Quinn vehicle, and the other circumstances already mentioned, amounted to restraints of this type.
In speaking of “restraints comparable to a formal arrest,” we do not understand the Supreme Court to have required Miranda warnings in situations other than “custody” as traditionally understood. Since Miranda, the touchstone to the need for Miranda warnings has been whether or not a suspect is “in custody.” Miranda warnings must be given when a person is in custody even if in his own bedroom and in familiar surroundings. Orozco v. Texas, 394 U.S. 324, 89 S.Ct. 1095, 22 L.Ed.2d 311 (1969). See also Mathis v. United States, 391 U.S. 1, 3-4, 88 S.Ct. 1503, 1504-05, 20 L.Ed.2d 381 (1968) (Miranda warnings must be given to one in custody even if questions do not pertain to case for which he is being held).
Conversely Miranda warnings are not required when the suspect is not in custody. In Beckwith v. United States, 425 U.S. 341, 96 S.Ct. 1612, 48 L.Ed.2d 1 (1976), a suspect not in custody was questioned by agents for three hours without prior Miranda warnings. The Court held that Miranda warnings were not required even though he was already the focus of the criminal investigation. Even when questioning occurs in the stationhouse, a suspect need not be given Miranda warnings if he went there voluntarily and there was no such restriction on his freedom as to render him in “custody.” California v. Beheler, 463 U.S. 1121, 1125, 103 S.Ct. 3517, 3520, 77 L.Ed.2d 1275 (1983). In Beheler an individual was questioned without Miranda warnings in the stationhouse after he had reported a homicide in which he was apparently involved. The police took him to the stationhouse but advised him he was not under arrest. Finding there had not been a restraint on freedom of movement such as is associated with formal arrest, the Court ruled that Miranda warnings were not needed. In Oregon v. Elstad, 470 U.S. 298, 105 S.Ct. 1285, 84 L.Ed.2d 222 (1985), where the Court ruled that, since Miranda violations are not constitutional, evidence obtained after them is not subject to the “fruit of the poisonous tree” test, the Court observed that “the task of defining ‘custody’ is a slippery one, and ‘policemen investigating serious crimes [cannot realistically be expected to] make no errors whatsoever.’ ” Id., 105 S.Ct. at 1293.
During Terry stops, the lower courts have held that Miranda warnings are not required. United States v. Jones, 543 F.2d 1171 (5th Cir.1976), cert. denied, 430 U.S. 957, 97 S.Ct. 1604, 51 L.Ed.2d 807 (1977); United States v. Hickman, 523 F.2d 323 (9th Cir.1975), cert. denied, 423 U.S. 1050, 96 S.Ct. 778, 46 L.Ed.2d 639 (1976); United States v. Thomas, 396 F.2d 310 (2d Cir. 1968). In Berkemer v. McCarty, 468 U.S. 420, 104 S.Ct. 3138, 82 L.Ed.2d 317 (1984), the Supreme Court similarly declined to require Miranda warnings during a traffic stop. Id. at 437,104 S.Ct. at 3148. But, as noted, the Berkemer Court went on to warn that, when in the course of a Terry stop a person is “subjected to restraints comparable to those of a formal arrest,” he must be advised of his Miranda rights. Id. at 441, 104 S.Ct. at 3151.
[161]*161It is not clear whether the Berkemer Court thought that a Terry stop could ever retain that character once the police used “restraints comparable to those of a formal arrest.” Perhaps the Court only meant to emphasize the need for Miranda warnings after a de facto, as well as after a “formal,” arrest. In any event, for reasons already discussed, we do not see the present circumstances as involving restraints “comparable to those of a formal arrest.” While appellee here was detained awhile for purposes of confirming or dispelling the officers’ suspicions, a reasonable man in appellee’s position would not have believed that he was under arrest at the time, and pressures that sufficiently impaired the free exercise of his privilege against self-incrimination were not imposed. Berkemer v. McCarty, 468 U.S. at 437, 104 S.Ct. at 3148. Appellee Quinn is a lawyer and felt free to ask that the dog be removed from the trunk of his car and to refuse to answer one of Agent Steadman’s questions. That the agent parked his car behind appellee’s, and hence “blocked” it, did not, under the circumstances that prevailed, indicate that appellee was being placed in custody. Hickman, 523 F.2d at 327; United States v. Montos, 421 F.2d 215, 221-23 (5th Cir.1970). The officers reacted reasonably and non-coercively in the circumstances they were confronted with. It may be, as the lower court said, that the situation was “fraught with pressure” for Streifel and Quinn. They could scarcely have welcomed police questioning at the time. But the psychological pressure experienced when confronted at the scene by police is not the same as “restraints comparable to those of a formal arrest.” Berkemer, 468 U.S. at 441, 104 S.Ct. at 3151. Compare Oregon v. Mathi-ason, 429 U.S. 492, 495, 97 S.Ct. 711, 713, 50 L.Ed.2d 714 (1977) (Miranda warnings not required where suspect not in custody simply because questioning takes place in what court considers a “coercive environment”).
In summary, we hold that the lawful Terry stop continued up and through the point when the sniff test was performed, requiring no probable cause but only reasonable suspicion that defendants had committed or were about to commit a crime when they were stopped. The results of the dog sniff gave the officers probable cause to search appellee’s car. The search revealed enough evidence to warrant an arrest. At no point in the sequence of events did a custodial situation necessitating Miranda warnings materialize. Therefore, the statements made to the officers, the results of the canine sniff, and the fruits of the searches of the car are all admissible into evidence.
The suppression order is reversed.