The FBI called off the search for Cooper last year, reassigning the lone agent on the case, according to the New York Times. They say they did so because the decades-long investigation was taking "investigative resources and manpower" from "programs that more urgently need attention." Effectively ending the investigation was "really an attempt by the bureau to spare the office from irritating calls, wacky emails and more," said Geoffrey Gray, a journalist who's written a book on the investigation.