Crossfire (1947)

Joseph "Sammy" Samuels is found beaten to death in his Washington, D.C. apartment by his girlfriend, Miss Lewis. Capt. Finlay of the police department is the lead investigator into the murder, which seemingly has to do with a group of four recently demobilized military men that Sammy and Miss Lewis had drinks with earlier that evening in a bar. Those four are "Monty" Montgomery, Arthur "Mitch" Mitchell, Floyd Bowers, and Floyd's friend Leroy. Indeed, Monty, who is questioned first by Finlay as he wanders by Sammy's apartment during the investigation, confirms that he, Floyd and Mitch were in Sammy's apartment earlier having drinks with Sammy, which explains why Finlay found Mitch's wallet in the apartment. On the surface, Mitch seems to be the most likely candidate as the murderer based on Monty's story that Mitch was drunk and out of sorts. A fifth demobilized military man, Peter Keeley - Mitch's roommate - confirms Mitch's tenuous mental state over his uncertain future, especially with his wife back in Chicago, but knows sensitive Mitch is not the type of person who could be a murderer. Keeley himself tries to find the missing Mitch to get his story and hopefully a confirmable alibi for the time of the murder. Keeley and Finlay at times seem to be working at cross purposes, but both come to the realization of the identity of the murderer about the same time. Without hard evidence or a witness, Finlay believes the key to conviction lies with Leroy.

IMDb: https://www.imdb.com/title/tt0039286