Hatley has been jailed for 40 years with the possibility of parole
A US Army master sergeant convicted of the 2007 murder of four Iraqi detainees has been sentenced to life in jail.
A jury of eight officers and NCOs handed the sentence to Master Sgt John Hatley during a court martial at a US base in southern Germany.
Hatley, 40, is the most senior of seven soldiers allegedly involved. Two have been convicted of murder and two admitted to lesser charges.
He was acquitted over an incident where a wounded insurgent was shot dead.
As well as the prison sentence, which comes with the possibility of parole, Hatley's rank will be reduced to private and he will be dishonourably discharged.
Hatley, who had denied the charges, showed no emotion as his guilty verdict was read out on Wednesday at the US Army's Rose Barracks in southern Germany.
The soldiers that Hatley led were stationed at a highly exposed combat post in West Rashid, which in early 2007 was one of the most violent neighbourhoods in Baghdad.
When they found four Iraqi men not far from a cache of weapons, including sniper rifles, just a week after one of their own sergeants had been shot and killed, they took the law into their own hands, says the BBC's Kevin Connolly in Washington.
With no real evidence against them the detainees should have been released, our correspondent says.
Instead they were bound, blindfolded and summarily killed. It is thought their bodies were dumped in a canal but they have never been found.
Because of that absence of physical evidence, Hatley was convicted on the strength of witness statements including those from the two other soldiers already convicted of the killings.
Capt Derrick Grace, for the prosecution, said testimony had pointed to "a complete breakdown of discipline and crimes that are among the worst of a soldier".
"On two separate occasions, the accused became the judge, jury and executioner."
Hatley is one of seven soldiers allegedly involved in the case and the third to be convicted for murder.
In February, Sgt Joseph Leahy, 28, was sentenced to life in prison for his role in the case and last month Sgt Joseph Mayo, 27, was sentenced to 35 years in prison.