A former soldier sentenced to life for raping and killing a teenage Iraqi girl and using a shotgun to gun down her family died in an Arizona prison over the weekend in what officials suspect was a suicide. Steven Dale Green was the first American soldier charged and convicted under the Military Extraterritorial Jurisdiction Act, a law signed in 2000 that gives the federal government jurisdiction to pursue criminal cases against American citizens and soldiers for acts committed in foreign lands, AP reported. The federal Bureau of Prisons Spokesman John Stahley said staff members at the federal penitentiary in Tucson, Ariz., found the 28-year-old Green, of Midland, Texas, unresponsive in his cell on Saturday. Stahley said Green's death is being investigated as a suicide. Green was a private in the 101st Airborne Division based at Fort Campbell on the Kentucky-Tennessee state line when he deployed to Iraq. Green and three other soldiers went to the home of an Iraqi family in Mahmoudiya, Iraq, near a traffic checkpoint in March 2006. At the home, Green shot and killed three members of the al-Janabi family before becoming the third soldier to rape 14-year-old Abeer Qassim al-Janabi before killing her. He was convicted and sentenced in 2009. Three other soldiers. Jesse Spielman, Paul Cortez and James Barker, are serving lengthy sentences in the military prison at Fort Leavenworth, Kan., for their roles in the attack. Each is eligible for parole in 2015. Green was discharged from the military in May 2006 after being found to have a personality disorder.