The UK's Power Slam magazine recently did an interview with Rob Van Dam. They asked him questions regarding the Chris Benoit double/murder suicide: Q: Okay. Moving on to the Benoit tragedy. Having known Chris for years, you must have been shocked when you heard that he'd murdered his wife and son.
A: Honestly, I'm not even convinced that he did it.
Many people like myself who knew Chris feel like it wasn't Chris who did that. That could mean lots of things: it could mean that someone else actually did it -- which I know is kinda hard to make sense out of, with all the investigations that took place. But that's still as believable, if not more believable, than believing Chris -- that good, respectable person we knew -- committed this horrific act.
It could mean that some kind of demon or evil spirit somehow entered his body. We can't scientifically explain something like that; but many of us believe that the body can be possessed. Again, that, as far-fetched as it may sound, is just as believable as thinking that Chris Benoit was capable of (killing his wife and son).
Lastly, the best scientific explanation we have is that Benoit had brain damage from the concussions and trauma to his head, which could have led to dementia.