A third suspect, the alleged ringleader, remains on the loose and is believed to be in hiding in Syria, The Times of London said. A fourth man was handed a life sentence, later reduced to 18 months on appeal.

Hassan, 59, was shot in the back of the head as she stood blindfolded and gagged. She had been snatched from her car by eight gunmen in Baghdad on Oct. 19, 2004.

Married to an Iraqi man and a Baghdad resident for 30 years, Hassan was working for the aid agency Care International when she was captured.