Defendant Edemiro A. Fernandez was indicted by a federal grand jury for possession of cocaine with intent to distribute in violation of 21 U.S.C. § 841(a)(1) (1988). Fernandez filed a motion to suppress evidence. After an evidentiary hearing, the magistrate judge recommended denying Fernandez’s motion to suppress. The district court adopted the magistrate’s Report and Recommendation in its entirety. Fernandez entered a conditional guilty plea reserving his right to appeal the denial of his motion to suppress on Fourth Amendment grounds. After reviewing the record, we reverse.
I.
Trooper Lance Bushnell of the Utah Highway Patrol was patrolling southbound on Interstate 15 near Nephi, Utah when he observed a blue GMC pickup truck with a camper shell traveling northbound. He noticed the windows appeared to be tinted darker than permitted under Utah law. Bushnell went to the next turnaround, turned north onto the highway, and traveled about eight or nine miles before he caught up with the truck, which was apparently traveling fast. At no time did Bushnell clock the truck’s speed or plan to stop it for a speeding violation. When Bushnell eventually caught up with the truck, he pulled alongside it to visually confirm that the windows were too dark. He noticed the driver’s side window was one third down and that the driver, Fernandez, glanced over at him. The truck then pulled partially over into the emergency lane on the right side of the highway and traveled there for approximately a quarter of a mile at reduced speed. Bushnell had not yet activated the patrol lights of his vehicle. Bushnell considered the driver’s behavior unusual and suspicious. He dropped back behind the truck, and the truck reentered the travel lane of the highway and resumed its speed. Bushnell then activated his lights and pulled the truck over for excessively tinted windows and improper lane travel.
Bushnell approached the vehicle and asked for Fernandez’s driver’s license and registration. Both documents were in Fernandez’s name. Bushnell felt a “tension in the air” and noticed Fernandez’s hand was trembling when he reached for his registration. Aplt. App., Suppression Hearing, 1/8/92, at 24, 26 (hereinafter Aplt.App.). Blanch, the passenger, was sleeping on the front seat next to Fernandez, and a young boy was behind the front seat. During the encounter Blanch woke up and appeared startled upon seeing a trooper in the window of the truck. He sat stiffly during the encounter. Bushnell asked for and received Blanch’s identification.
In response to Bushnell’s inquiries, Fernandez and Blanch informed Bushnell that the boy was Blaneh’s son and that they were taking him from Los Angeles to Chicago to visit his grandmother. This seemed unusual to Bushnell who asked if it wasn’t more cost-effective or efficient to fly the boy to Chicago instead of driving. Mr. Fernandez replied that they had checked on airline tickets and mentioned a price of $500. Bushnell then returned to his patrol car with Fernandez’s license and registration. Bushnell testified that due to the truck occupants’ nervousness, he became suspicious and concerned for his safety. He therefore radioed for backup and requested a NCIC computer check on the vehicle and its occupants.
Officer Mangelson arrived after six or seven minutes to assist Bushnell. As Bushnell returned to the driver’s side of the truck, Mangelson approached the passenger side. Bushnell had a warning citation and Fernandez’s license and registration in his possession. He also retained Blanch’s identification. Without returning these papers, Bushnell started to ask a series of questions. He asked if there were any weapons in the truck and also inquired whether there were any *876drugs or other contraband in the vehicle. Fernandez replied in the negative, and both occupants said they did not use drugs. Bushnell asked Fernandez why he was so nervous. During his testimony at the suppression hearing, Bushnell could not recall Fernandez’s response, but he did recall that the answer was unsatisfactory. Fernandez and Blanch appeared to get increasingly nervous as the encounter continued.
Bushnell testified that Fernandez was not free to leave once he had been stopped. Without returning Fernandez’s license or registration, or Blanch’s identification, Bushnell asked for permission to look in the truck. Fernandez and Blanch started to exit the vehicle without answering Bushnell verbally so Bushnell asked Fernandez again, “Do you understand I want to search the truck?” Fernandez replied, “I understand, go ahead.” Brief of Aplt., App. at 10 (Magistrate Report & Recommendation) (hereinafter Report); Aplt.App. at 39.
Bushnell and Mangelson started searching the truck together. As they pushed the front seat forward, they observed a compartment covered by a piece of carpet. When they pulled back the carpet, they saw through a seam in the compartment what appeared to be numerous kilograms of cocaine. The troopers arrested Fernandez and Blanch. An inventory search of the truck uncovered 123 kilograms of cocaine in various hidden compartments.
The magistrate judge concluded that the stop was not pretextual because the Utah Highway Patrol Unit to which Bushnell was assigned regularly enforces the tinted window law by arresting or issuing citations to Utah drivers and warning out-of-state drivers who are in violation of the law. The magistrate judge found that Fernandez’s driver’s license and vehicle registration were not returned to him until after the arrest, but held that Bushnell had reasonable suspicion justifying the continued detention. Finally, although the magistrate judge found that “at the time of the consent to search Fernandez was still being detained,” Report at 20-21, he nevertheless held that Fernandez’s consent to search was voluntary. He denied the motion to suppress and the district court adopted the Report and Recommendation in its entirety.
II.
In reviewing the Fourth Amendment claims of Fernandez, we uphold the factual findings of the district court unless they are clearly erroneous. United States v. Walker, 933 F.2d 812, 815 (10th Cir.1991), cert. denied, — U.S. -, 112 S.Ct. 1168, 117 L.Ed.2d 414 (1992). We are mindful that at a hearing on a motion to suppress, the credibility of the witnesses and the weight given to the evidence, as well as the inferences and conclusions drawn therefrom, are matters for the trial judge. United States v. Werking, 915 F.2d 1404, 1406 (10th Cir.1990). However, the ultimate determination of reasonableness under the Fourth Amendment is a question of law which we review de novo. Walker, 933 F.2d at 815.
Fernandez raises three Fourth Amendment claims. First, he contends the stop was pretextual because a reasonable officer under the circumstances would not have made the stop in the absence of an invalid purpose. Second, he argues that his detention beyond the time necessary to issue a citation was not based on reasonable suspicion. Finally, he contends that he did not give free and intelligent consent to search his truck. We address each of these claims in turn.
A.
A pretextual stop occurs when an officer uses some legal justification to stop a person or vehicle in order to investigate unrelated criminal matters for which the officer lacks reasonable suspicion. See United States v. Guzman, 864 F.2d 1512, 1515 (10th Cir.1988). In Guzman, we defined the test to be applied to claims of pretextual stop. To determine whether an investigative detention is unconstitutional as a pretext we ask “ ‘not whether the officer could validly have made the stop, but whether under the same circumstances a reasonable officer would have made the stop in the absence of the invalid purpose.’ ” Id. at 1517 (quoting Unit*877ed States v. Smith, 799 F.2d 704, 709 (11th Cir.1986)).
Applying the Guzman test, the district court concluded that the stop was not pretextual. It stated that Bushnell and the “Utah Highway Patrol unit to which Trooper Bushnell was attached enforced the Utah window tinting law on a regular basis.” Aplt.App. at 8,11. The district court noted that it is the policy of the Utah Highway Patrol Unit to which Bushnell is assigned to issue warning tickets to out-of-state vehicles in violation of the tinted window law and that Bushnell issued sixty-three such warnings between July and November of 1991, as well as seven citations. Thus, it appears that Bushnell routinely stops and issues warning citations to out-of-state motorists for excessively tinted windows. The routine practices of an individual officer, however, will not preclude a finding of pretext if an objectively reasonable officer under the same circumstances would not have made the stop absent an invalid purpose. See Guzman, 864 F.2d at 1517.
There is considerable objective evidence in the record suggesting that, although this stop was not unusual for Bushnell, a reasonable officer in the same circumstances might not have stopped Fernandez’s truck in this case. For example, while Bushnell issued sixty-three warning citations for tinted windows over a five month period, statistics for Bushnell’s unit reveal that in the same five month period one officer issued no warnings, two officers issued one warning each, one officer issued three warnings, and another officer issued twenty warnings. See Aplt. App., exh. at 13. Assuming, in accordance with the stated policy of Bushnell’s unit, that each of these warning citations resulted from the stop of an out-of-state vehicle such as the truck at issue in this appeal, it appears that Bushnell regularly stops and issues warnings to such motorists significantly more than his counterparts.1 The evidence reveals a similar trend with respect to the improper lane travel violations. Bushnell issued forty-four warnings for improper lane travel in a five month period while his five fellow officers issued between zero and five warnings. Id. In addition to these statistics, the record reveals that Bushnell observed the tinted window violation from across the highway while travelling in the opposite direction as Fernandez’s truck. He then drove to the next turnaround, crossed over the highway, and pursued the truck for approximately eight or nine miles before actually pulling it over. We question whether such a stop would be “business as usual” for a reasonable officer under the same circumstances. See Werking, 915 F.2d at 1408.
Looking at all this evidence together, it is not a foregone conclusion that a reasonable officer under the same circumstances would have stopped Fernandez’s truck, even viewing the alleged violations together as Bushnell did.2 Despite evidence suggesting this stop may have been pretextual, however, we expressly decline to decide this issue, as we reverse on other grounds.
B.
Fernandez next contends that he was unlawfully seized when Bushnell detained him without reasonable suspicion beyond the time necessary to issue a citation. With respect to investigative detentions of automobiles it is well established in this circuit that
*878[a]n officer conducting a routine traffic stop may request a driver’s license and vehicle registration, run a computer check, and issue a citation. When the driver has produced a valid license and proof that he is entitled to operate the car, he must be allowed to proceed on his way, without being subject to further delay by police for additional questioning.
Guzman, 864 F.2d at 1519 (citations omitted); see also Walker, 933 F.2d at 815-16.
Given the factual finding that Bushnell retained Fernandez’s license and registration until after the arrest was made, there is no question that Fernandez was seized when Bushnell returned to the truck and started asking questions unrelated to the traffic stop. The issue we face is whether Bushnell had objectively reasonable suspicion justifying the continued seizure of Fernandez.
Relying on the truck’s improper lane travel, Fernandez’s “extreme nervousness,” and the passenger’s “unusual behavior,” the Report adopted by the district court concluded the seizure was based on reasonable suspicion. Report at 21-22. The district court distinguished the present case from Guzman and Walker because “this case does not involve a ‘routine traffic investigation.’ ” Id. at 21. Finally, the court relied largely on United States v. Walraven, 892 F.2d 972 (10th Cir.1989), as support for the conclusion that reasonable suspicion existed. While we do not find the factual findings of the lower court to be clearly erroneous, we disagree with its legal conclusion and hold that reasonable suspicion did not exist in this case.
Bushnell’s continued detention of Fernandez can only be justified if “specific and articulable facts and rational inferences drawn from those facts [gave] rise to a reasonable suspicion” of criminal activity. Werking, 915 F.2d at 1407. An officer’s “inchoate and unparticularized suspicion or ‘hunch’ ” is insufficient to give rise to reasonable suspicion. United States v. Sokolow, 490 U.S. 1, 7, 109 S.Ct. 1581, 1585, 104 L.Ed.2d 1 (1989); Terry v. Ohio, 392 U.S. 1, 27, 88 S.Ct. 1868, 1883, 20 L.Ed.2d 889 (1968). We determine whether reasonable suspicion exists by examining the totality of the circumstances. Sokolow, 490 U.S. at 8, 109 S.Ct. at 1585-86; United States v. Ward, 961 F.2d 1526, 1529 (10th Cir.1992).
Fernandez does not argue that Bushnell lacked reasonable suspicion to make the initial traffic stop, but that he was unlawfully detained beyond the time necessary to issue the initial traffic citation. See United States v. Soto, 988 F.2d 1548, 1555 (10th Cir.1993) (“When [the officer] questioned defendant about matters unrelated to the initial traffic stop, the detention entered a new phase.”). At the time Bushnell returned to the truck with the warning citation and began asking questions about drugs and weapons, the evidence shows that, although Fernandez and his passenger were nervous, Fernandez had a valid driver’s license and registration, both in his own name, and that Fernandez and his passenger Blanch gave a consistent and very plausible explanation of their travel.3 The three factors relied upon by the district court are insufficient to create reasonable suspicion under the circumstances of this case. First, the improper lane travel violation partly justified the initial stop of Fernandez and was sufficiently minor to warrant only a warning citation. This is not a case where a defendant’s evasive action or failure to pull over promptly in response to a trooper’s flashing lights is an objective indication of something more serious than a minor traffic infraction. See United States v. Sharpe, 470 U.S. 675, 682 n. 3, 105 S.Ct. 1568, 1573 n. 3, 84 L.Ed.2d 605 (1985) (evasive actions of defendants’ vehicles one of many factors supporting reasonable suspicion); United States v. Paleo, 967 F.2d 7, 9 (1st Cir.1992) (flight of vehicle police signalled to stop for speeding one of several factors creating reasonable suspicion of drug activity); Walraven, 892 *879F.2d at 975 4 (defendants’ failure to stop ear promptly in response to police car’s flashing lights and siren supports finding of reasonable suspicion). In this case, Fernandez immediately pulled over when Bushnell activated his flashing lights. While Bushnell found Fernandez’ improper lane travel unusual, as we noted supra at n. 2, an innocent cautious driver might well believe an officer who pulls alongside him on the highway and stays there looking at him intends for him to pull over. Under the circumstances, reducing one’s speed and moving into the emergency lane hardly gives an officer reasonable suspicion to believe some other serious crime had been or was being committed.
The second and third factors relied upon to support the claim of reasonable suspicion involve the unusual nervousness of Fernandez and the startled awakening and stiff demeanor of passenger Blanch. We have repeatedly held that nervousness is of limited significance in determining reasonable suspicion and that the government’s repetitive reliance on the nervousness of either the driver or passenger as a basis for reasonable suspicion “in all cases of this kind must be treated with caution. It is common knowledge that most citizens, and especially aliens, whether innocent or guilty, when confronted by a law enforcement officer who asks them potentially incriminating questions are likely to exhibit some signs of nervousness.” United States v. Millan-Diaz, 975 F.2d 720, 722 (10th Cir.1992); see also United States v. Peters, 10 F.3d 1517, 1521 (10th Cir.1993) (“ While a person’s nervous behavior may be relevant, we are wary of the objective suspicion supplied by generic claims that a Defendant was nervous or exhibited nervous behavior after being confronted by law enforcement officials....’”) (quoting United States v. Hall, 978 F.2d 616, 621 n. 4 (10th Cir.1992)); Walker, 933 F.2d at 817; Guzman, 864 F.2d at 1520. The lower court’s heavy reliance on nervousness as an important factor establishing reasonable suspicion is even more troublesome given the complete lack of evidence in the record that Bushnell had any prior knowledge of Fernandez or Blanch to make an evaluation of their behavior. In this respect we-find the instant case strikingly similar to United States v. Bloom, 975 F.2d 1447 (10th Cir.1992), where this court held that a border patrol agent’s “statement that Defendant appeared “very nervous’ and ‘somewhat excited’ is a subjective evaluation of Defendant’s behavior.” 975 F.2d at 1458. The court went on to say that
Nothing in the record indicates whether Agent Oehoa had any prior knowledge of Defendant, so we do not understand how Agent Ochoa would know whether Defendant was acting nervous and excited or whether he was merely acting in his normal manner. Rather, Defendant’s appearance to Agent Ochoa is nothing more than an “inchoate suspicion or hunch”....
Id. (citations omitted).
In making its reasonable suspicion determination below, we think the lower court failed to recognize an important distinction between this case and our other cases in this area. More specifically, a defining characteristic of our traffic stop jurisprudence is the defendant’s lack of a valid registration, license, bill of sale, or some other indicia of proof to lawfully operate and possess the vehicle in question, thus giving rise to objectively reasonable suspicion that the vehicle may be stolen. See, e.g., Soto, 988 F.2d at 1556 (car registration allegedly in uncle’s name and defendant completely failed to respond when asked for uncle’s address); United States v. Horn, 970 F.2d 728, 732 (10th Cir.1992) (unnotarized bill of sale written on back of envelope and title in different person’s name); United States v. Turner, 928 *880F.2d 956, 959 (10th Cir.), cert. denied, — U.S. -, 112 S.Ct. 230, 116 L.Ed.2d 187 (1991) (ear not registered to defendant or passenger); United States v. Pena, 920 F.2d 1509, 1514 (10th Cir.1990) (no registration or proof driver entitled to operate car), cert. denied, 501 U.S. 1207, 111 S.Ct. 2802, 115 L.Ed.2d 975 (1991); United States v. Arango, 912 F.2d 441, 447 (10th Cir.1990) (no credible proof that defendant lawfully possessed truck), cert. denied, 499 U.S. 924, 111 S.Ct. 1318, 113 L.Ed.2d 251 (1991); United States v. Rivera, 867 F.2d 1261, 1264 (10th Cir.1989) (defendant unable to produce ownership papers); United States v. Gonzalez, 763 F.2d 1127, 1130 (10th Cir.1985) (driver licensed in New York, driving car with California plates and registered to California owner, and carrying unsigned title); United States v. Obregon, 748 F.2d 1371, 1376 (10th Cir.1984) (car rented in another’s name, driver not listed as authorized driver, and driver unable to provide means of contacting lessee); cf. Guzman, 864 F.2d at 1519 (no reasonable suspicion where officer received proper license and registration and confirmed car not stolen).
While nervousness may also appear as a factor in many traffic stop cases, we have never held that by itself it creates a reasonable suspicion of criminal activity. In the instant case, Fernandez provided Bushnell with a valid license and registration, both in his own name. At no time did Bushnell attempt to justify the continued detention of Fernandez based on any specific, objective factors supporting a reasonable inference that the truck was stolen, that the defendant was trafficking in drugs, or that he was committing any other criminal offense. Cf., e.g., United States v. Corral, 899 F.2d 991, 992 (10th Cir.1990) (spare tire out of place and bulge in tire well basis of reasonable suspicion); United States v. Stone, 866 F.2d 359, 362 (10th Cir.1989) (officer’s smell of patchouli oil often used to mask smell of marijuana basis of reasonable suspicion that car carried contraband).
After examining the totality of the circumstances, we conclude there was insufficient evidence in this case to establish reasonable suspicion justifying the continued detention of Fernandez. Bushnell’s testimony regarding his “sixth sense,” his detection of a “tension in the air,” and his belief that something was “afoot,” strongly suggests he was acting more on an unparticularized hunch than on reasonable and objective suspicion.5 See *881United States v. Lyons, 7 F.3d 973, 976 (10th Cir.1993) (holding stop pretextual where officer relied on “sixth sense” that driver was impaired and noting such reliance “is merely the manifestation of a hunch that something foul is afoot”).
In support of the lower court’s finding below, the dissent points to two factors that we find particularly unconvincing under the circumstances of this case. First, the dissent suggests that Bushnell’s initial thought that Fernandez might be driving under the influence somehow justified his continued detention. Even though Bushnell may have been suspicious of this possibility initially, however, he testified that this was not one of the reasons he actually stopped Fernandez. Aplt.App. at 56. Moreover, after he made the initial stop, Bushnell “administered no roadside sobriety tests; did not request the defendant submit to blood, breath, or urine tests; and issued no citation for driving while impaired.” Lyons, 7 F.3d at 975. Indeed, the record is devoid of anything indicating that after their initial encounter Bushnell thought Fernandez was impaired or that he continued to detain and question Fernandez to determine if he was impaired. This factor is therefore totally irrelevant to any analysis. Second, the dissent points to Bushnell’s concern for his safety as a justification for Fernandez’s continued detention. As the record reveals quite clearly supra at n. 5, however, Bushnell’s safety concerns stem from the same subjective hunch, “tension in the air,” and nervousness that we have already discounted as an adequate basis for reasonable suspicion.6
For the reasons set out above, we hold that Trooper Bushnell did not have a sufficient objective and particularized basis supporting his suspicions, and that his continued detention of Fernandez therefore violated the Fourth Amendment.
C.
A search preceded by a Fourth Amendment violation remains valid if the consent to search was voluntary in fact under the totality of the circumstances. Guzman, 864 F.2d at 1520; see also Ward, 961 F.2d at 1534. The government bears the burden of proving the voluntariness of consent, Schneckloth v. Bustamonte, 412 U.S. 218, 222, 93 S.Ct. 2041, 2045, 36 L.Ed.2d 854 (1973), and that burden is heavier when consent is given after an illegal stop, United States v. Recalde, 761 F.2d 1448, 1457 (10th Cir.1985); see also United States v. Deases, 918 F.2d 118, 122 n. 1 (10th Cir.1990) (“Having concluded that the initial stop of Deases’ car was lawful, the government does not have the ‘heavier burden’ in connection with the consent issue which it would have if the initial stop was unlawful.”), cert. denied, — U.S. -, 111 S.Ct. 2859, 115 L.Ed.2d 1026 (1991). The government must establish that Fernandez’s consent to search is “sufficiently an act of free will to purge the primary taint of the illegal [seizure], [or] it must be suppressed as fruit of the poisonous tree.”7 *882United States v. Maez, 872 F.2d 1444, 1453 (10th Cir.1989); see also United States v. Lowe, 999 F.2d 448, 451 (10th Cir.1993); United States v. Mendoza-Salgado, 964 F.2d 993, 1011 (10th Cir.1992); Ward, 961 F.2d at 1534; Walker, 933 F.2d at 817. When examining the totality of the circumstances, no single fact is dispositive but three factors are especially significant: “the temporal proximity of the illegal stop and the consent, any intervening circumstances, and the purpose and flagrancy of [the official] misconduct.” Guzman, 864 F.2d at 1520, 1521 (adopting these factors from Brown v. Illinois, 422 U.S. 590, 603-04, 95 S.Ct. 2254, 2261-62, 45 L.Ed.2d 416 (1975)).
The district court found that no language problem existed between Fernandez and Bushnell, and that Bushnell retained Fernandez’s documentation at the time he requested consent to search the truck. We do not disturb these factual findings, as they are not clearly erroneous. See Mendoza-Salgado, 964 F.2d at 1011. The record shows that Bushnell asked Fernandez if he would mind if the officer searched the truck. Without replying verbally, Fernandez and his passenger Blanch opened the doors of the truck and started to get out. Bushnell then said to Fernandez, “Do you understand I want to search the track?”, to which Fernandez replied, “I understand, go ahead.” Aplt.App. at 39. Although Bushnell retained Fernandez’s documentation, neither Bushnell nor the assisting trooper Mangelson informed Fernandez that he could refuse to give his consent or that he was free to leave the scene, both important factors in our consideration. See, e.g., Ward, 961 F.2d at 1533 (informing an individual of his constitutional rights, particularly Fourth Amendment rights, is important because it shows the individual that the police are prepared to respect his assertion of those rights); Recalde, 761 F.2d at 1459 (consent lacking where defendant never told he was free to leave by officer holding ticket, driver’s license, and registration); United States v. Gonzalez, 763 F.2d 1127, 1133 (10th Cir.1985) (consent fruit of illegal detention where officer retained defendant’s documentation and did not inform defendant he was free to leave when handing him consent form). Although informing a defendant of his right to refuse consent is not a prerequisite to establishing voluntary consent, Schneckloth, 412 U.S. at 234, 93 S.Ct. at 2051, we consider it a factor “particularly worth noting,”8 Florida v. Bostick, 501 U.S. 429, -, 111 S.Ct. 2382, 2385, 115 L.Ed.2d 389 (1991); see United States v. Mendenhall, 446 U.S. 544, 548-49, 100 S.Ct. 1870, 1873-75, 64 L.Ed.2d 497 (1980) (verbal advisement to defendant she could decline consent “especially significant”); Ward, 961 F.2d at 1533.
Examining the encounter between Bushnell and Fernandez in light of the fact that Bushnell had already extensively questioned Fernandez,9 that a second officer had arrived on the scene, that Bushnell retained Fernandez’s documentation, and that Fernandez was not informed of his right to refuse consent or to leave the scene, we do not consider their verbal exchange so unambiguous that Fernandez’s consent was clearly voluntary in fact. In addition, the three “Brown factors” *883on which we place special emphasis all indicate Fernandez’s consent was tainted by the prior unlawful seizure. First, Fernandez verbally acquiesced to the search only moments after the illegal detention and questioning by Bushnell. See Ward, 961 F.2d at 1534 (consent not voluntary where “only minutes” passed after illegal seizure); Maez, 872 F.2d at 1447, 1455, 1456 (taint of illegal arrest not purged where consent form signed thirty minutes after illegal arrest); Recalde, 761 F.2d at 1459 (no voluntary consent where only “several minutes” elapsed between illegal detention and signing of consent form); cf., Mendoza-Salgado, 964 F.2d at 1012 (considered alone, thirty to forty-five minute time period between illegal entry and defendant’s consent reveals little about defendant’s “decision to permit the search”); see also Brown, 422 U.S. at 604-05, 95 S.Ct. at 2262-63 (statement given less than two hours after illegal arrest fruit of poisonous tree). Second, there were absolutely no intervening circumstances between the illegal detention and Fernandez’s consent. Both of these factors suggest that there was no “break in the causal connection between the illegality and the evidence thereby obtained.” Recalde, 761 F.2d at 1458.
Finally, analyzing the third Brown factor, we conclude that the purpose and flagrancy of Bushnell’s conduct also weighs heavily against a finding of voluntary consent. Bushnell testified that there was a “tension in the air,” and that he believed something was “afoot.” Aplt.App. at 24, 29. Bushnell felt Fernandez and Blanch were “definitely nervous,” yet he had no idea what they were nervous about. Id. at 32. He stated with respect to the nervous mannerisms he observed in Fernandez and Blanch that: “I perceived they know something that I don’t know, there is something making them nervous and also as an officer, I feel an obligation and responsibility to pursue whatever is making them nervous.” Id. at 29. Thus, the illegal detention here “had a quality of purposefulness” in that Bushnell continued to detain Fernandez based solely on a tension in the air and his vague hunch that something was afoot, with “the hope that something might turn up.” Brown, 422 U.S. at 605, 95 S.Ct. at 2262; see Recalde, 761 F.2d at 1459; see also Ward, 961 F.2d at 1535. By illegally detaining Fernandez, failing to return his documentation, and failing to inform him of both his right to leave the scene and to refuse consent, Bushnell’s conduct was sufficiently egregious that it tainted Fernandez’s consent.
Law enforcement officials must obey the requirements of the Fourth Amendment when performing their duties. We place particular emphasis on the Fourth Amendment “concern that evidence not be obtained by exploitation of illegal police conduct.” Walker, 933 F.2d at 817-18. Accordingly, we hold that any consent Fernandez may have given was not “sufficiently Jree of duress and coercion so as to remove the taint of the illegal detention.” Recalde, 761 F.2d at 1459. We therefore REVERSE the district court’s denial of Fernandez’s motion to suppress.
REVERSED and REMANDED.
. The dissent criticizes our use of statistics concerning Bushnell's issuance of warning citations and cites United States v. Harris, 995 F.2d 1004, 1005 (10th Cir.1993), for the proposition that it is immaterial whether an officer would issue a formal citation or an informal warning. Harris 's reasoning is inapplicable, however, where, as here, the stated policy of Bushnell’s unit was to issue warnings to out-of-state vehicles and citations to Utah vehicles. The individual officer’s statistics on the issuance of warning tickets and citations therefore provides some objective measure of the comparative frequency with which the officers make each type of stop.
. When Bushnell pulled alongside Fernandez and started to scrutinize the vehicle, Fernandez reduced his speed and pulled his truck into the emergency lane. When Bushnell did not activate the lights and dropped back behind Fernandez, the pickup truck reentered the highway and resumed its speed. It is highly plausible that Fernandez thought he was being pulled over, and we find it interesting that Bushnell could not recall Fernandez's response when Bushnell asked why he pulled into the emergency lane. Contrary to the dissent’s assertion, this lack of memory is an objective factor a district court may consider when making its judgment concerning pretext.
. The fact that Fernandez and Blanch were driving Blanch's son to visit a relative in Chicago instead of flying him there allegedly aroused Bushnell’s suspicions. However, the district court quite correctly concluded that many people do not like or can not afford air travel. The court therefore did not consider the suspects' *879form of travel as a factor contributing to reasonable suspicion. Report at 20 n. 6.
. We think the lower court relied too heavily on 'Walraven in finding reasonable suspicion below. Walraven is distinguishable from the instant case in that defendants in Walraven failed to pull over promptly when the officer activated his overhead lights and siren. They also conferred with one another and actively observed the police officer during the pursuit. It is well recognized that a defendant’s intentional flight from police officers may be used as circumstantial evidence of guilt. See United States v. Slater, 971 F.2d 626, 636 n. 4 (10th Cir.1992). Furthermore, unlike Bushnell’s vague sense that something was afoot in the present case, the officer in Walraven reasonably suspected the detained defendants were drug couriers. 892 F.2d at 974.
. The record is replete with testimony showing Bushnell acted based on his subjective, unpartic-ularized hunch that something was wrong. When asked to describe the encounter with the suspects, Bushnell stated: "Definitely tension in the air, the way I perceived that is that they knew something I didn't know.” Aplt.App. at 24. Referring to the nervous reaction of Fernandez and Blanch, Bushnell stated:
My experience has shown that when someone acts and displays those type of mannerisms there is something afoot that I said before[,] I perceived they know something that I don't know, there is something making them nervous and also as an officer, I feel an obligation and responsibility to pursue whatever is making them nervous.
Aplt.App. at 29.
In one passage Bushnell is asked to tell the Court what he notices about traffic stops that result in further criminal inquiry or sometimes arrest for crimes other than traffic violations:
Q [by United States] Tell the Court what that might be?
A [by Bushnell] Generally without fail, there are exceptions, but there, the first thing that I will notice is nerves, they always exhibit these nervous mannerisms. There is almost and you can, you know, sixth sense whatever you want to call it, but it is almost a tension in the air. You can feel the tension and I think that is what keeps officers, you know, officers safe or safety keeps them alive. They can feel that tension there.
Q Is this based on your experience?
A Yes, sir.
Q And based on training you have received?
A No, I don't think you can train to pick up on that. That is part of nervousness and tension in the air.
Aplt.App. at 23-24 (emphasis added).
At one point the government asked Bushnell:
Q [by United States] Did you have any idea specifically what you were suspicious about or worried about?
A [by Bushnell] No, I would like to have known myself. That is why I was curious enough to check into it. I don't know whether they were wanted[,] whether they had just done something they feel that they could be caught for, maybe they just stole some gas or whatever. They were definitely nervous about something.
Aplt.App. at 32 (emphasis added).
Finally, when asked on cross-examination about what specifically gave him concern for his safety Bushnell responded:
*881A [by Bushnell] I'm always, when someone gets nervous like that around me I’m always concerned for my safety being jeopardized, sir.
Q [by counsel for Fernandez] This nervousness that you talked about?
A: Yes, sir, tension in the air and stuff.
Aplt.App. at 56-57 (emphasis added).
While Bushnell's hunch turned out to be correct, we simply can not conclude from his testimony that he acted on the basis of "specific reasonable inferences” as required by Terry v. Ohio, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968).
. The dissent notes the dangers police officers face during the course of their duty and suggests that Bushnell’s concerns for his safety somehow justified the continued detention and questioning of Fernandez about guns and drugs. We are cognizant of the very real dangers officers face, including when making traffic stops, see Pennsylvania v. Mimms, 434 U.S. 106, 110, 98 S.Ct. 330, 333, 54 L.Ed.2d 331 (1977), but an investigative detention must nonetheless be supported by reasonable suspicion. Furthermore, contrary to the dissent’s suggestion, our holding today does nothing to diminish the capacity of officers to deal with their safety concerns. An officer may always call for backup, as Bushnell did here, as long as the officer does not detain a suspect without reasonable suspicion. In addition, if an officer lacking reasonable suspicion wishes to address his safety concerns by detaining a suspect for questioning about guns and drugs, he may attempt to do so on a consensual basis. See Soto, 988 F.2d at 1557.
. The district court concluded that Fernandez’s consent was voluntary. Because it found that the continued detention of Fernandez was lawfully based on reasonable suspicion, however, the *882court did not perform a taint analysis. A remand on this issue is unnecessary because the proceedings below " 'resulted in a record of amply sufficient detail and depth from which the determination may be made.' ” Guzman, 864 F.2d at 1521 n. 10 (quoting Brown v. Illinois, 422 U.S. 590, 604, 95 S.Ct. 2254, 2262, 45 L.Ed.2d 416 (1975); see United States v. Lowe, 999 F.2d 448, 451 n. 5 (10th Cir.1993); United States v. Mendoza-Salgado, 964 F.2d 993, 1011 (10th Cir.1992); United States v. Ward, 961 F.2d 1526, 1534 n. 7 (10th Cir.1992); United States v. Maez, 872 F.2d 1444, 1454 n. 13 (10th Cir.1989).
. The fact that a defendant is informed of his constitutional rights does not necessarily mean his consent will be voluntary in fact. See Maez, 872 F.2d at 1455-56 (holding taint of illegal police actions not purged even where defendant signed consent-to-search form after Miranda warnings and both written and oral notice of right to refuse); Gonzalez, 763 F.2d at 1133 (holding consent obtained from consent-to-search form fruit of illegal detention); Recalde, 761 F.2d at 1452-59 (taint not purged by Miranda warning and written notification of right to refuse).
. "When examining the totality of the circumstances to determine 'if in fact the consent to search was coerced, account must be taken of subtly coercive police questions.." Mendoza-Salgado, 964 F.2d at 1011 n. 9 (quoting Schneckloth, 412 U.S. at 229, 93 S.Ct. at 2049).