He was in a shoot-out with him at that location and they heard that single shot before the cabin burned down. Journalists can't say for sure due to political correctness because there hasn't been a dental record check or DNA testing, but it's pretty obvious he's dead. That's also why they call people a "suspect" even when it's obvious beyond a doubt they are guilty. I doubt he had time to place a dead body in there in the midst of a shoot-out and then escape.