I've just watched on DVR the latest 'Castle' which I like. SPOILERS may follow.
It was a variant plot structure I think that I've seen before.
First you have a ring of people. You meet them as one of them was murdered.
Then you go back over that ring of people again, and on a fair number of them, the ones that get elevated to 'suspect' (and this format is similar to process of elimination with several suspects before the final unveiling) you have a payoff of information.
"No, I'm not the murderer because despite my sweet appearance, I'm actually a drunk, and I was passed out blitzed at the ER that night."
Its the type of thing you wouldn't want to confess, but it saves you from the murder rap so you do.
In this case, you had a mastermind who arranged for his 'friends' to look like they were guilty. I don't think that is necessary for this format.
I'm not sure how to get a verser in to this type of murder mystery. Hmmm, I suppose one way would be for a verser to meet another verser at a remote hotel (typical mystery stuff--isolate the group), and have the hero verser spot something the victim to be verser has that he wants.
They discuss trading it, and the victim then agrees to the deal.
So far, the hero probably has no clue what's coming.
Since the verser agreed to the deal, he's disowned the treasure. He goes back to his room alone. If the hero really wants to come with him, the victim remembers that he left the treasure in the hotel safe and it can't be opened right now.
The important thing is to get the victim away from his friend for a few minutes.
Victim gets killed. He verses out, but the disowned treasure is left behind.
Now the hero can be motivated by ....
1. Desire for justice.
2. Vengeance for his friend if they are friends.
3. The murderer has the treasure. He has to find the murderer to get the treasure back.
4. Possibly the treasure is some sort of powerful item that works in this low bias world, and is not at all the sort of thing a murderer should have. Maybe its a hypno-beam gun in a world with no clue such a thing is possible. So a sense of social responsibility might drive the hero.
I think something like that could work.