Write a short story scene (approx. 1000 words) that utilizes a non-linear narrative structure. The story should take place in a noir setting and involve a detective discovering a betrayal. The narrative must alternate between three distinct timelines: the present investigation, the memory of the crime, and a flashback to the initial partnership. Use sensory details to distinguish the timelines without explicitly stating the date. Ensure that the revelation in the present timeline recontextualizes the events in the past timelines.