Want a murder mystery party game? I Didn’t Do It! is a great game for up to eight players. Each player is a suspect except one who is the investigator. The suspects have to account for themselves over the last 24 hours, only they may not be able to substantiate everything they say, and more evidence can contradict what they’ve said.
The mechanism for finding the murderer isn’t to establish evidence, it’s by finding inconsistencies in the alibis that the suspects give that the investigator hones in on who the murderer is. So, say enough to be convincing, but don’t say too much or you might become the prime suspect.