Terrance Jewett filed this action under 42 U.S.C. § 1983 against Officer Dale Anders, a Milwaukee police officer. He alleges that Officer Anders unlawfully arrested him and used excessive force in effectuating the arrest in violation of the Fourth Amendment, as made applicable to the states by the Fourteenth Amendment. He also alleges that Officer Anders deprived him of liberty without due process of law in violation of the Fourteenth Amendment. Officer Anders filed a motion for partial summary judgment on the unlawful arrest and deprivation of liberty claims. He also asserted qualified immunity with respect to these allegations. The district court denied his motion. Officer Anders then timely filed an interlocutory appeal in this court.
For the reasons set forth in this opinion, we reverse the judgment of the district court.
I
BACKGROUND
A.
In this interlocutory appeal from a denial of qualified immunity on summary judgment, we have jurisdiction to consider only the purely legal question of whether, for purposes of Officer Anders’ qualified immunity defense, a given set of facts demonstrates a violation of clearly established constitutional law.
Leaf v. Shelnutt,
On December 21, 2003, the Milwaukee Police Department was investigating an attempted homicide that had occurred the previous day. In connection with this investigation, Officer Dale Anders was ordered to meet several other officers at the Wal-Mart store on Capitol Drive and 60th Street. The officers were under instructions to apprehend Andre Thompson, who worked in the automotive department of the Wal-Mart. The Milwaukee police suspected that Thompson had been the perpe *820 trator of the previous day’s shooting; the officers had been advised that Thompson was armed. 1
Officer Anders and his partner, both of whom were in full police uniform, arrived at the Wal-Mart in a marked police vehicle. Officer Anders parked the squad car in a position west of the store. While in the Wal-Mart parking lot, he observed an individual peer out of a door located at the south side of the Wal-Mart building. Shortly thereafter, he observed a young black male exit the Wal-Mart through a door located on the north side of the building; this individual subsequently was identified as Terrance Jewett. This sequence of events caused Officer Anders to become suspicious. Believing that Mr. Jewett might be Thompson, Officer Anders started following him in the marked police car. As Officer Anders neared, Mr. Jewett turned and ran back toward the Wal-Mart.
Upon seeing Mr. Jewett run, Officer Anders exited his vehicle and ordered him to stop. Officer Anders claims that he identified himself as a police officer; Mr. Jewett maintains that he heard someone yelling for him to stop but that the individual did not identify himself as a police officer. Mr. Jewett continued running until he reached the Wal-Mart door and then started to pound frantically on it.
Having caught up with Mr. Jewett, Officer Anders claims that he believed that he and his partner were in a dangerous situation. Mr. Jewett had failed to obey his commands. Moreover, the Officer believed that Mr. Jewett was Thompson and, on the basis of the earlier briefing, that he was armed. Consequently, Officer Anders sought to bring Mr. Jewett within his physical control by performing a “wall stun” on Mr. Jewett: he placed his hands against the middle of Mr. Jewett’s back and pushed his chest against the door. R.26 ¶ 31. Officer Anders then put his forearms under Mr. Jewett’s armpits and pulled him toward the ground. When he had Mr. Jewett face down on the ground, Officer Anders grabbed Mr. Jewett’s hands, brought them behind his back and handcuffed him.
Once he had secured Mr. Jewett in handcuffs, Officer Anders conducted a search of his person. The Officer retrieved Mr. Jewett’s identification from his pocket, which identified him as Terrance Jewett rather than Andre Thompson. Officer Anders placed Mr. Jewett inside the squad car. At this point, Sergeant Pamela Holmes arrived on the scene and spoke briefly with Mr. Jewett. Officer Anders confirmed Mr. Jewett’s identification and issued him a municipal citation for obstructing a police officer based on Mr. Jewett’s failure to obey his commands to stop. 2 Officer Anders then released Mr. Jewett. According to Mr. Jewett, the incident lasted approximately thirty to forty minutes; Officer Anders claims that Mr. Jewett was detained for twenty minutes.
B.
Mr. Jewett filed this section 1983 action against Officer Anders. Specifically, Mr. Jewett claims that Officer Anders arrested him unlawfully and used excessive force to effectuate the arrest in violation of the *821 Fourth Amendment, as made applicable to the states by the Fourteenth Amendment. Mr. Jewett also claims that Officer Anders deprived him of liberty without due process of law in violation of the Fourteenth Amendment. 3 Officer Anders moved for summary judgment on qualified immunity grounds and on the merits with respect to all claims except for the excessive force claim. The district court denied his motion.
The district court determined that there was no evidence that Officer Anders had the physical description of the suspected perpetrator of the December 20th attempted homicide that he was investigating. The district court noted that
[i]n his affidavit, Officer Anders states that “Officers had been advised that we were to proceed to [Wal-Mart], to look for and apprehend one Andre Thompson, who had a birth date of January 24, 1981, and who had a physical description of being a black male, 6'3" tall, and approximately 216 pounds.”
R.37 at 4 n. 1. The court ruled, however, that this assertion constituted inadmissible hearsay. As a result, it determined that Officer Anders had no other basis for comparing Mr. Jewett’s physical characteristics with the description of Thompson. The district court then concluded that Officer Anders did not have probable cause to arrest Mr. Jewett solely based on Mr. Jewett’s location, the automotive department of Wal-Mart and his attempt to escape after being commanded to stop by Officer Anders. The court accordingly denied Officer Anders’ motion for summary judgment on the unlawful arrest claims.
Next, the district court analyzed whether Officer Anders was entitled to qualified immunity. The court set forth the appropriate standard under
Saucier v. Katz,
II
DISCUSSION
A. Standard of Review
We review de novo a district court’s denial of summary judgment on qualified immunity grounds.
Sullivan v. Ramirez,
B. Interlocutory Jurisdiction
Although a district court’s denial of summary judgment usually is an unappealable
*822
interlocutory order, an “exception to this general rule exists for a district court’s denial of qualified immunity on summary judgment.”
White v. Gerardot,
Because of this limitation on our interlocutory jurisdiction, our review of a denial of qualified immunity is framed either by the facts as assumed by the district court or by the facts as set forth by the plaintiff.
White,
C. The Qualified Immunity Framework
The doctrine of qualified immunity shields from liability public officials who perform discretionary duties.
Belcher v. Norton,
The Supreme Court of the United States has articulated a two-part test for qualified immunity: (1) whether the facts, taken in the light most favorable to the plaintiff, show that the defendant violated a consti
*823
tutional right; (2) whether that constitutional right was clearly established at the time of the alleged violation.
Saucier,
Qualified immunity is an affirmative defense.
Sparing v. Vill. of Olympia Fields,
D. Officer Anders’ Detention of Mr. Jewett
We now turn to the first step in the Saucier analysis and explore whether Officer Anders violated the constitutional rights of Mr. Jewett.
The first issue that we must decide is whether Officer Anders’ detention of Mr. Jewett constitutes an investigatory
Terry
stop or a complete arrest. If Mr. Jewett’s detention constituted only an investigatory stop, the Fourth Amendment requires the lower standard of reasonable suspicion.
United States v. Kirksey,
We begin by examining whether Officer Anders’ actions, as alleged by Mr. Jewett, can be characterized as a constitutional investigatory stop authorized by
Terry.
Mr. Jewett had a right to be free from a
Terry
stop unless Officer Anders had reasonable suspicion.
Terry,
In determining whether Officer Anders’ action was justified at its inception, we must consider whether it was based on the applicable standard of reasonable suspicion. The Supreme Court has considered whether an individual’s unprovoked flight is sufficient to give the officer reasonable, particularized suspicion to warrant an investigatory stop.
Wardlow,
[Ujnprovoked flight is simply not a mere refusal to cooperate. Flight, by its very nature, is not “going about one’s business”; in fact, it is just the opposite. Allowing officers confronted with such flight to stop the fugitive and investigate further is quite consistent with the individual’s right to go about his business or to stay put and remain silent in the face of police questioning.
Id.
at 125,
In examining whether Officer Anders’ actions were “reasonably related in scope to the circumstances which justified the interference in the first place,”
Terry,
392 NS. at 20,
Turning to the case before us, we believe that. Officer Anders’ detention of Mr. Jewett, at the time that the Officer initiated the action, did not exceed the permissible bounds of an’investigatory detention under Terry. We also believe that the measures employed by the Officer were reasonable when evaluated under-the totality of the circumstances.
At the moment that he decided to conduct an investigatory stop of Mr. Jewett, Officer Anders was at the WalMart to search for and arrest Andre Thompson. Thompson was suspected by the police of having perpetrated the shooting and attempted murder that had occurred the previous day. Officer Anders had been advised that Thompson could be armed, and he reasonably considered Thompson to be dangerous to himself, his partner and others.
5
Officer Anders observed an individual peering out of the door of the Wal-Mart where Thompson
*826
was thought to be. The Officer then observed the individual, later identified as Mr. Jewett, exit the Wal-Mart. Officer Anders drove toward him in order to determine whether the individual engaging in this suspicious behavior was Thompson. As Officer Anders neared, Mr. Jewett fled without provocation and continued running despite Officer Anders’ calls for him to stop.
6
Once Mr. Jewett reached the door of the Wal-Mart, he began pounding frantically to gain entrance. Upon reaching him, Officer Anders pushed him into the door, brought him face down onto the floor and handcuffed him. Given Officer Anders’ reasonable belief that Mr. Jewett was Thompson, who was wanted for attempted murder and whom the police believed to be armed, this procedure was “appropriate to accomplish the purpose of [the] investigatory stop.”
'Weaver,
Once he had secured Mr. Jewett, Officer Anders frisked him, and, during the frisk, he retrieved Mr. Jewett’s identification from his pocket, which identified him as Terrance Jewett rather than Andre Thompson. We have held that an officer may retrieve an individual’s identification from his wallet.
United States v. Brown,
The length of the detention is a factor in determining whether an investigatory stop was transformed into a formal arrest. Although Officer Anders claims that the entire incident — from the time that Mr. Jewett fled until the time that he was released — lasted twenty minutes, we are required, given the procedural posture of this case, to assume Mr. Jewett’s version of thirty to forty minutes. The length of Mr. Jewett’s detention alone did not convert the investigatory stop into an arrest.
8
Indeed, we have noted that “[t]here is no bright-line rule as to how long an investigative detention may last; instead we look to whether the police diligently pursued a means of investigating that was likely to confirm or dispel quickly their suspicions.”
United States v. Adamson,
Consequently, we conclude that Officer Anders’ investigatory stop of Mr. Jewett was “reasonably related in scope to the circumstances which justified the interference in the first place.”
9
Terry,
*828 Conclusion
Accordingly, we hold that Mr. Jewett’s detention fell within the bounds of a constitutional investigatory stop. We cannot say that Officer Anders acted unreasonably in detaining Mr. Jewett to determine his identity. Officer Anders therefore is entitled to qualified immunity as to Mr. Jewett’s claims of unlawful arrest and deprivation of liberty. The judgment of the district court is reversed, and the case is remanded for further proceedings. Officer Anders may recover his costs of this appeal.
Reveesed and Remanded
Notes
. Officer Anders submitted an affidavit to the district court stating: "Officers had been advised that we were to proceed to [the WalMart] to look for and apprehend one Andre Thompson, who had a birth date of January 24, 1981, and who had a physical description of being a black male, 6'3" tall, and approximately 216 pounds.” R.27 ¶ 4, at 1.
. Mr. Jewett was cited for violating Milwaukee Code of Ordinances § 105-138, entitled "Resisting or Obstructing an Officer.” The citation eventually was dismissed by the City of Milwaukee on its own motion.
. Mr. Jewett’s complaint states: "Plaintiff was denied his right to due process not to be deprived of liberty without due process of law when he was shoved against a door, searched, thrown to the ground, tightly cuffed, and forced to sit on his hands in a squad car even after the officers were aware that he was not involved in any crime.” R.l ¶ 44.
. Qualified immunity protects those officers who make a reasonable error in determining whether there is reasonable suspicion to conduct a
Terry
stop.
Lindsey v. Storey,
. We pause briefly to address the district court’s evidentiary ruling, which bears on Officer Anders’ knowledge immediately prior to his detention of Mr. Jewett. The district court excluded Officer Anders' statement that ’’[o]fficers had been advised that we were to proceed to [the Wal-Mart] to look for and apprehend one Andre Thompson, who had a birth date of January 24, 1981, and who had a physical description of being a black male, 6'3" tall, and approximately 216 pounds.” R.37 at 4 & n. 1.
Our jurisdiction necessarily must extend to review of the district court’s exclusion as inadmissible hearsay of Officer Anders’ testimony regarding the information that he received from his superiors when he was dispatched to the Wal-Mart to apprehend Andre Thompson. That issue is intertwined with the issue of qualified immunity, and its consideration is "necessary to ensure meaningful review of the qualified immunity question.”
Henry v. Purnell,
*826
In the district court’s view, the statement in question was inadmissible hearsay. We respectfully cannot agree. The statement is offered to demonstrate the effect of this information on Officer Anders as he encountered Mr. Jewett and to explain the Officer’s actions in detaining Mr. Jewett,
United States v. Norwood,
Mr. Jewett disputes the veracity of Officer Anders’ assertion that he had been given Thompson’s height and weight. Specifically, Mr. Jewett maintains that Officer Anders inserted into his police notebook Thompson’s weight and height only after he had detained Mr. Jewett. Given the posture of this case, we may not rely on that portion of the statement. Mr. Jewett, however, does not take issue with Officer Anders’ assertion that he had been told to proceed to the Wal-Mart to arrest Thompson, a black male of approximately 22 years, the suspected perpetrator of the previous days’ attempted homicide. Therefore, we consider only that portion of the statement in our analysis.
. Mr. Jewett submits that Officer Anders' actions were unreasonable because Mr. Jewett was not running away from the police, but rather running back toward the Wal-Mart door because he wanted to try to catch the door before it closed and locked. Mr. Jewett claims that he had left his keys inside the Wal-Mart and that he had run back to retrieve them. Mr. Jewett also maintains that he did not see Officer Anders in the marked police squad car or in his police uniform, and he did not hear Officer Anders identify himself as a police officer. Nevertheless, Mr. Jewett’s subjective motivations for running away are irrelevant, as is the fact that he did not hear Officer Anders identify himself as a police officer. When determining whether a police officer has reasonable suspicion to conduct an investigatory stop, we "look to the officerfs] knowledge at the time of the [detention], not the suspect’s."
Marshall ex rel. Gossens v. Teske,
.Officer Anders' motion for partial summary judgment did not request summary judgment on the merits or on qualified immunity grounds as to Mr. Jewett’s excessive force claim. We acknowledge that our holding that Officer Anders’ use of force in effectuating the investigatory stop did not convert the encounter into a formal arrest is in tension with Mr. Jewett’s excessive force claim. The parties have not briefed this matter on appeal, and, more important, Mr. Jewett’s excessive force claim is not before us.
.
See,
e.g.,
Cady v. Sheahan,
. Mr. Jewett's complaint also sought redress because Officer Anders "deprived him of liberty without due process of law.” R.l ¶ 44. Mr. Jewett’s complaint does not explain whether the focus of his claim is a deprivation of procedural or substantive due process.
*828
The Supreme Court has cautioned that a substantive due process claim may not be maintained where a specific constitutional provision protects the right allegedly violated — in this case, the Fourth Amendment — and, therefore, we construe Mr. Jewett's claim as an alleged deprivation of procedural due process.
United States v. Lanier,
