Season 5: Episode 21 - The Past, Present and Murder

The Past, Present and Murder: When a body comes flying out of media mogul Robert Dunbrook's highrise office window and then disappears, Robert Dunbrook is their main suspect. Given his history with Mac, Dunbrook requests Mac be taken off the case, however, Sinclair insists that he stay on. Meeting nothing but conflict, Mac and the CSI's work the case and discover the last person to enter Dunbrook's office (as "witnessed" by Dunbrook's hi-tech biometric security) was Ann Sinclair -- a high-powered "fixer" killed several months earlier whose flashdrive filled with potentially dangerous information to many of the city's elite was stolen from the police evidence locker. The CSI's discover the missing body was that of a dishonored FBI agent who had been searching for the flashdrive to restore his career.The FBI agent discovered Dunbrook had the flashdrive and was trying to steal it when Dunbrook's son discovered him and killed him.