Ex-SEALs, online gaming maven among Benghazi dead NEW: The fourth American killed was another former SEAL, Tyrone Woods, official says Security officer Glen Doherty was searching for anti-aircraft missiles, source says: (CNN) -- Sean Smith was a computer expert with an online alter ego legendary in the gaming world. Glen Doherty and Tyrone Woods were former Navy SEAL commandos working as diplomatic security officers. All three died with U.S. Ambassador Chris Stevens in the assault on the American consulate in the Libyan city of Benghazi. Details of how they met their fates in the Mediterranean city that had been the cradle of Libya's 2011 revolution were just beginning to emerge Thursday. Woods' identity was confirmed Thursday evening by a U.S. official, and no further information about him was immediately known. But a diplomatic source told CNN that Doherty was in Libya to search for shoulder-fired anti-aircraft missiles -- a mission given high priority after the fall of longtime Libyan strongman Moammar Gadhafi. Doherty grew up in Massachusetts with a passion for the outdoors, particularly the mountain West, his family said. Outside the family's home in Woburn, near Boston, his sister remembered him as "our American hero." The 42-year-old graduated from high school in 1988 in neighboring Winchester, where flags were displayed at half-staff on Thursday. After college in Arizona and stints as a "ski bum" and raft guide in Utah, Doherty joined the Navy and became a member of the elite Navy SEAL commandos in 1995, his family said in a statement. He had planned to leave the service after knee surgery in 2001, but after the al Qaeda attacks on New York and Washington, he "was not allowed to to leave and didn't want to," his family said. Doherty served two tours of duty in Iraq, starting with the U.S. invasion in 2003, before leaving the military in 2005. He then became a private security contractor, working in Afghanistan, Pakistan and Yemen -- a job that took a toll on his home life and contributed to a divorce, his family said. He also joined the advisory board of the Military Religious Freedom Foundation, a group that has battled religious intolerance in the U.S. armed forces. Its president, former Air Force officer Michael "Mikey" Weinstein, said he was "in a state of shock" after learning of Doherty's death. He also co-authored a 2010 book, "The 21st-Century Sniper: A Complete Practical Guide," with former comrade Brandon Webb. In a statement accompanying the family's, Webb said, "Don't feel sorry for him, he wouldn't have it." "He died serving with men he respected, protecting the freedoms we enjoy as Americans and doing something he loved," Webb said. Smith's death was among the first reported in the Benghazi fracas. Secretary of State Hillary Clinton eulogized him Wednesday as a 10-year veteran of the Foreign Service, an information management officer who had served in Iraq, South Africa, Canada and the Netherlands. In real life, he was an Air Force veteran with a wife, a son and a daughter. CNN's Chris Lawrence, Elise Labott and Chuck Johnston contributed to this report.