SPOILERS AHEAD!!!!
Episode 402-
Curious who everyone thinks has been feeding the walkers rats and who burned Karen and David? Thoughts? I'm thinking it isn't going to be obvious so my thoughts are 1 of two scenarios: First, Herschel went to check on them in the night and both had died and turned, and he killed them both and simply finished the job by dragging them out and burning them in hopes of stopping the spread of the infection. Second, it could be a possible suicide. Karen (or David?) could have known they were dying and took matters in to their own hands by killing the other sickly and dragging them to the outside, burning them, then dousing their self with gas, lighting the fire, then shooting/stabbing.
Some are pointing the finger to Bob, Carl, or Carol. I don't think it was any of them. Too easy.