(NBC News) — Tonight, on a two-hour “Dateline,” Florida firefighter Derrick Dorsey returns home after a long shift to find his wife, Kim, unresponsive in their bedroom. “Dateline” correspondent Andrea Canning examines the puzzling scene investigators found and what could have happened.

This “Dateline” episode entitled “In Cold Blood” features interviews with Derrick Dorsey, Detective T.K. Waters and more.

Here’s a preview of Canning’s report:

Assistant Chief T.K.Waters was responding to a call about a possible suicide.

T.K. WATERS: It was chaos. And you could tell that something really horrible had happened here. You walk in initially, and you see our victim lying at the foot of the bed. You can see, even as dark as it was in the room, the lighting wasn’t very, very good. It was just a – it was just a scene that – that read that something horrible had happened here.

Not far from where Kim lay they found a knife. They saw patches of blood soaked into the carpet and specks of red on one wall. And on another, something that jumped right out at them.

T.K. WATERS: There had been some gunshots in a wall. And you could see the bullet holes in the wall.

Officers later found those bullets and the gun that fired them. A pink-handled revolver had been tossed on the bedroom floor. There was something else they noticed.

LARRY KUCZKOWSKI: There was a pool cue – a broken pool cue – in the bedroom. And it was the – what I call the fat end of the pool cue.

Even as their eyes strained against the dark, they could make out the bruises all over Kim. It was clear: she had not killed herself.

Watch tonight’s “Dateline” mystery tonight at 8 p.m. on KTAL NBC 6.