(CNN) -- A former U.S. soldier convicted five years ago of murdering an Iraqi family died Saturday, two days after an apparent suicide attempt in his Arizona prison cell, authorities said.
Steven Green was found unresponsive last Thursday, according to the Federal Bureau of Prisons.
The deputy chief medical examiner with Pima County, Dr. Eric Peters, said the cause of death was suicide by hanging.
In 2009, Green was found guilty in U.S. District Court in Kentucky of raping a 14-year-old Iraqi girl and murdering her, her parents and her 6-year-old sister in the town of Yusufiya, about 20 miles south of Baghdad. The crimes occurred three years before the conviction.
Prosecutors sought the death penalty but a jury couldn't reach a unanimous decision.
He issued a public apology for his crimes, one the relatives of the victims didn't accept.
Green, who was sentenced to multiple life sentences without possibility of parole, told the family he was "truly sorry for what I did in Iraq."
"I helped to destroy a family and end the lives of four of my fellow human beings, and I wish that I could take it back, but I cannot," Green said, reading a statement at a victim impact hearing. "And, as inadequate as this apology is, it is all I can give you."
The relatives decried Green's sentence and testified about how the heinous crime had shattered their lives, and how it will haunt them always.
Green said that he knew "you wish I was dead, and I do not hold that against you. If I was in your place, I am convinced beyond any doubt that I would feel the same way."
Green was tried in a civilian court in Paducah, Kentucky, because he had already been discharged from the Army by the time his crimes surfaced.
He was the last of five soldiers who served in the 101st Airborne Division, based at Fort Campbell, Kentucky, to be convicted for the crimes and their subsequent cover-up.
CNN's Dave Alsup contributed to this report.