Ok, so here is the situation...

The group I'm playing with consists of a Cleric (Redemptionist Firebrand background), a Scum, a Tech-priest, and myself an Arbitrator.

During the course of our investigation of some underground caves that may or may not have a mutant/daemon infestation we came upon a citizen who had squirreled himself away. After some initial questioning my Arbitrator feels he is hiding something but in the process of further questioning the citizen falls unconscious. The cleric says he is going to drag the citizen out of the room and light him up (he has already set a blaze one citizen who had seen too much and gone insane and threatened another 10 guardsman, recovering in an infirmary, with the same fate).

I intervene and say that I have further questions for the citizen, but the cleric now says that he is going to just poor the fuel on the citizen right here then. I tell him to stand down this citizen is hiding something and I want to know what it is and once I'm done then he can purge him. The cleric ignores me and opens his gas tank, I swing the butt of my gun at his chest (missing) and again tell him to stand down. The cleric then says that he is going to light me up and attempts to douse me in fuel but also misses. It's at this time the Scum in the group empties a 3 round burst into the citizen's face and says the point is moot let's move on trying to keep us from killing each other.

How would you deal with the murder a citizen who potentially held information pertaining to your investigation (the Scum), the intent to commit murder of the citizen (the Cleric), and the intent to commit murder of an Arbitrator (the Cleric)?

I held off from doing anything because we are trapped underground for at least two days with who knows what in front of us. The more living bodies around me, the more likely we are to make it out. But it's a little hard to overlook the attempt on my character's life.