This was interesting to me:

On my second playthrough I was in a hurry, so I only rescued the Deputy from the ground floor of the Bison Steve hotel and casino in Primm. I thought I would leave the second and third floor to clear up later. In the meantime, I finished the "My Kind of Town" quest by installing NCRF ex-convict Meyers as Primm's new sheriff. When I returned to the town about ten days later, I was in need of experience because I was close to going up in level. So I thought I would clear out the second and third floors of the Bison Steve. I went there, and all the convicts were in their normal places, but they were all dead. Not looted-- they still had everything on them. There were blood trails in the hallways.

My only thought is that Meyers and his deputies promised to clean up the town-- so they must have killed them.

Has this happened to anyone else? Is my theory right?

If so, it's a nice little touch programmed into the quest. Another example of how some missions and areas are so polished and well done, yet other parts of the game are obviously unfinished.

I am playing on a PC, if this makes any difference.

Just thought I'd share that observation with you.

I made the bot sheriff and the same happened

Cool...but they were all dead before I found a new sheriff

Same here but its neat that they actually had the sheriff clear out the badguys there.