How long would they remain detectable by an autopsy in a county that didn't even want to spend $5k on DNA testing? How long was the body decaying before discovered. I do agree about the necrotizing venoms. But consider a black widow. You could be incapacitated, rendered helpless for a day or so, and become sufficiently dehydrated to be essentially delirious after recovering from the bite proper. That would leave you in a state that, without assistance, you'd not die from the bite, but from starvation/dehydration several days later. How long is the toxin in the body?