Hopefully something very minor or something he was only in ancillary proximity to.
And friendly reminder, this site has very strong anti-libel rules. Don't make accusations or strong implications about what you think this may be about, and definitely don't help rumor mongers spread potentially false stories. If you don't see a major mainstream media outlet reporting on it, don't post or talk about it here. In other words, if a wordpress blog or a Twitter user with 78 followers claims to have inside knowledge, ignore it.