Riddle for you! I will let you know if you get it right in 3 hours. or more depends on if I'm on.

There is a murderer ok? He/She leaves a trail of clues on a various chain of crimes about who, when, where, why, and how the victim will be murdered. That day/night, the murderer is in the room with the victim, the detective, and him/herself. Two people die, yet the murderer only kills one. How is this possible?