It's very possible that Benoit did kill his family. Wrestling has a way of turning people into something they never thought they could be. There's only so many steroids, painkillers & other various substances you can pump into your body before your mind starts turning into applesauce.
Somebody posted a list of dead wrestlers & there's so many more out there that had fallen off of peoples radar. Mike Awesome committed suicide, Louie Spicoli OD'd, Pitbull #2 OD'd , Hercules Hernandez died of heart failure at 47, The Wall (Malice in TNA) died of heart failure at 36 and The Renegade (remember the fake Ultimate Warrior from WCW in the early 90's?) killed himself. Canadian Strongman Dino Bravo was executed gang style. Not to mention the wrestlers who are still alive and just sad to look at now...Jake Roberts is an alcoholic/crack addict, Bret Hart will never be the same after the concussions/strokes he's suffered, Steroids have destroyed Superstar Billy Graham's body and just look at the broken necks wrestlers have suffered and the drugs needed so that they can perform (Kurt Angle, Lita, Steve Austin, Buff Bagwell, Scott Steiner, etc, etc....)
I can not stand to see any child suffer at all, but I would imagine that there's probably more to this case than meets the eye. I would imagine Benoit was in a very strange place mentally.