Somebody is involved in something dirty, or just did something nasty. Could be The Government, could be The Mafia or The Syndicate, could be General Ripper, a Corrupt Corporate Executive or an Ancient Conspiracy. No matter what bad guy was involved, somebody saw it all, heard it all, or somehow caught wind of what's going down (or what went down), and the bad guy in question has found out about the witness. The most common motive for bad guys to go after innocent people and the reason that the FBI has the Witness Protection Program. Examples of He Knows Too Much include: