is determined by the information possessed by the officer at the moment the force is employed. Waterman v. Batton, 393 F.3d 471, 477 (4th Cir.2005). A mistaken use of deadly force, however, is not necessarily a constitutional violation under the Fourth Amendment: “a mistaken understanding of facts that is reasonable in the circumstances can render a seizure reasonable under the Fourth Amendment.” Milstead v. Killer, 243 F.3d 157, 165 (4th Cir.2001); see also Maryland v. Garrison, 480 U.S. 79, 87, 107 S.Ct. 1013, 94 L.Ed.2d 72 (1987) (“[T]he Court has recognized the need to allow some latitude for honest mistakes that are made by officers in the dangerous and difficult process of making arrests and executing search warrants.”); Henry v. Purnell, 501 F.3d 374, 382 (4th Cir.2007) (<HOLDING>). Before us, Officer Bullock vigorously
holding that the officer acted reasonably in shooting the decedent where the plaintiff did not directly counter the defendants evidence showing that the decedent matched the description of a suspect who threatened a victim with a knife was armed with a knife and ignored the officers instructions to drop it and jabbed it at the officer while taking steps toward him holding that evidence of recklessness by one officer in events leading up to shooting was immaterial in evaluating objective reasonableness of shooting officers decision to use deadly force in the situation he faced at time of shooting holding direct testimony tying a defendant to a gun was not required when the gun was found in the defendants truck and when the defendant had both ammunition for the gun and a rack in which it could have been kept holding that instruction on use of deadly force was not required where there was no evidence that decedent had attempted to assault appellant appellant could not retreat or that decedent was armed recognizing that shooting the decedent with a handgun when thinking it was a taser gun could be a reasonable mistake