(CNN) -- A U.S. Army sergeant was sentenced Thursday to life in prison without parole for gunning down five fellow service members at a combat stress clinic in Iraq.
The sentence handed down at Joint Base Lewis-McChord, near Tacoma, Washington, came after Sgt. John Russell pleaded guilty to the killings in a deal in which prosecutors agreed not to seek the death penalty.
The only question facing the judge, Col. David Conn, was whether Russell committed the slayings with premeditation, which the 48-year-old soldier disputed.
During a brief sentencing hearing, Conn ruled Russell killed with premeditation," meaning the sergeant could not be given a lesser sentence.
As part of last month's plea agreement, Russell described to the court how he killed Navy Cmdr. Charles Springle, Army Maj. Matthew Houseal, Sgt. Christian Bueno-Galdos, Spec. Jacob Barton and Pfc. Michael Yates Jr.
It was the first time Russell had publicly detailed what happened at the clinic. Russell, a communications specialist, was on his third deployment to Iraq.
His attorneys argued Russell suffers from post-traumatic stress disorder, depression and a brain injury from previous combat, which make him not fully responsible for the killings.
As part of the sentence, Russell was reduced in rank to a private and ordered dishonorably discharged from the Army, Maj. Barbara Junius, a military spokeswoman, said.