McGreevey was a Starfleet officer during the Dominion War. In 2375, he was serving at AR-558 when he was killed by the Jem'Hadar. He was known as very talkative which often annoyed fellow soldier Vargas, but Vargas was deeply affected when McGreevey died tending Vargas' wounds. (DS9 episode: "The Siege of AR-558", DS9 short story: "Requital")