So, what does a Police Inspector do during a Murder Game? Basically, you keep things going in an orderly fashion.

Begin by explaining the reason for the gathering, then have each person go over their previous statement. By the time everyone is finished, people will be criticizing each other and offering information like crazy.

Allow the suspects to question each other - you can use your "authority" to force someone to answer.

When you feel the time is right, tell everyone what information you have gathered during the past year. Phrase it as you like.

Don't accuse anyone, but feel free to pick up on comments and attitudes that you feel are misleading.

Hey, you have POWER - use it and enjoy it.
At the end, everyone gets to guess the truth.