An Air Force veteran who agreed to testify before Congress about secret government UFO programs died just months before the hearings of an accidental drug overdose. Matthew James Sullivan, 39, died at his home in Falls Church, Va., on May 12, 2024 from a lethal mix of alcohol, alprazolam, cyclobenzaprine and imipramine, according to the Northern District Office of the Chief Medical Examiner. The mysterious death is of "grave concern" to Rep. Eric Burlison (R-Mo.), who referred the matter for investigation to the FBI due to "implications for national security," according to a letter obtained by The Post. "Mr. Sullivan's death was a local Virginia medical examiner case, and the manner and circumstances of his of death raise substantial questions, as he was preparing to provide testimony to Congress," the April 16 letter addressed to FBI Director Kash Patel read. "The sudden and suspicious circumstances surrounding his death raise significant concerns about potential foul play and the safety of other individuals involved in this matter." The FBI indicated in a statement that Sullivan's death could be under investigation along with the dozen other missing or dead US scientists. Sullivan earned a Bronze Star for valor in Operation Enduring Freedom and later worked for the Air Force Intelligence Agency, National Air and Space Intelligence Center, and the National Security Agency.