A L Werker - He Walked by Night (1948)

Routinely driving home alone in the wee hours of the morning after his shift, LAPD Officer Robert Rawlins stumbles upon what he believes is a burglary, only the latest in a rash, many like this one at a radio store. In confronting the possible perpetrator, Rawlins is shot by the perpetrator - Rawlins eventually succumbing to his injuries - while the perpetrator is able to escape. Captain Breen assigns partnered Detectives Marty Brennan and Chuck Jones to lead the investigation, an especially difficult one for Marty who knew Rawlins personally. Beyond the routine procedure of the dragnet of local lowlife brought in for questioning which yields nothing, they garner few leads with the evidence at the scene, which includes the perpetrator's disabled vehicle filled with an arsenal of weapons, some electronic equipment, a pair of gloves and what turns out to be a vial of nitroglycerin, a discarded set of pick locks found in the bushes nearby, and a description from Rawlins, before he passed, of the perpetrator himself, the only eyewitness description. Although the detectives get a major break in some specialized electronic equipment that was stolen at a previous burglary turning up, they don't seem to be able to make any real major inroads in the case if only because the perpetrator is always one step ahead of them in seemingly being able to read their minds. To break the case, they, with a little help from the forensics, will have to figure out how the perpetrator, who has continued his crime spree, seems to know as much as he does about the progression of the investigation in its entirety.