Just one more thought..a while ago I was in a simular situation where a friend warned me about a man in the same way. I took her advise and turned down a gathering for some kayaking.
About a month later , I found out that the man really was the victim and my "good" friend was the agressor and she was turned down by this guy.
I know know him and his new girlfriend better and really kick myself for not going for my gut feelings on this.....