It's pretty simple how it can be done. Just have a murderer and victim picked from the cast, maybe the GM's OCs or maybe one of us, hell you could give us an option whether we'd prefer our characters to be victims or murderers. Then work out the logistics of the murder in PM, then just post the finding of the body in the IC plus the evidence. It's not that hard. To mask identity, the GM can simply describe the scenes and the conditions of the body.