A person can actually survive arsenic poisoning;he must have been given a MASSIVE amount,if that’s what happened.
Coolant mixed in a drink, perhaps.. Ethylene Glycol I think it’s called. It’s RAPIDLY absorbed by the body.
Could he have been given small amounts of arsenic over a long period of time?
I'm not up on my poisons. Can't they look at his hair to see if arsenic has been ingested and how long ago it was ingested? Kind of rings on a tree tell its's age.