In the 1980s, he was based in Albuquerque, where his duties included classified planning and analysis of NATO surveillance systems. He had top-secret clearance, but investigators said there was no indication he had given away classified information.

Captain Hughes, who was unmarried at the time he fled, had been temporarily assigned to the Netherlands on July 18, 1983, to work with NATO officers. He was slated to return to Albuquerque on Aug. 1, but never showed up. On Dec. 9, the Air Force declared him a deserter.

For years, the details of his disappearance remained a mystery. The Albuquerque Journal reported in early 1984 that Captain Hughes had left his car at the airport. Investigators said he was last seen withdrawing $28,500 from 19 bank branches. They raided his home and found to-do lists.

Air Force investigators interviewed friends, associates and co-workers, who said they did not know his whereabouts. Family members wondered if he had been abducted. Attempts by the Air Force to track him down at home and abroad were unsuccessful.

The Cold War was still years from ending and tensions with the Soviet Union were high, which left many wondering if there had been foul play. According to a 1986 article in The Los Angeles Times, intelligence officers believed that Captain Hughes had either defected to the Soviet Union or been captured by Russian agents. Captain Hughes, these officers said, had knowledge of top-secret launch procedures. “He is worth his weight in gold to the Russians,” one of them was quoted as saying.