The Naked City (1948)

Of the eight million stories in New York City, this story centers on Jean Dexter, a recently fired dress shop model who is found dead first thing one hot summer morning by her housekeeper Martha Swenson, Jean determined to have been rendered unconscious by chloroform before she was drowned alive in her apartment bathtub, her story which will touch several other individuals in the city either directly, indirectly or just in passing. Leading the investigation, veteran police detective, Lt. Dan Muldoon, and his team, including most specifically enthusiastic rookie Det. Jimmy Halloran, a young Long Island family man tasked with doing most of the legwork, follow up on the leads discovered in Jean's apartment and in questioning Swenson, those leads including a bottle of sleeping pills, she perhaps in a relationship with an only once seen older man named Philip Henderson, she having a friendship with a nicer younger man named Frank Niles, and a rare black star sapphire ring found on her person in addition to some other missing expensive but equally distinctive jewelry. In addition, Halloran questions those at the dress shop where she worked, there where he meets who was arguably Jean's best friend, fellow model Ruth Morrison. In bringing him in for questioning, Muldoon catches Niles in one lie after another, Muldoon who has to sift through if the reason for the lying is connected to the murder. Halloran tries to convince Muldoon that a dead body found floating in the East River, that death which occurred shortly after Jean's murder, seems like it is connected to this case. Beyond Muldoon sifting through Niles' lies, the key to the case seemingly is for them to find Philip Henderson, he and others who may be connected being able to hide among eight million others in the city, especially if they know the police are looking for them, discovering them which may rely on the effectiveness and efficiency of Halloran's legwork.

IMDb: https://www.imdb.com/title/tt0040636