This is a relatively current and interesting article about human Chimeras and about how science is now learning that the incidence of this anomaly is a lot more common than originally thought.

http://www.nytimes.com/2013/09/17/scien … wanted=all

Russian serial killer Andrei Chikatilo was a Chimera. His blood DNA was tested against the semen DNA found on the victims early on in the investigation and was not a match. It was another 12 years and a lot more murders before the connection was made.