Army Sergeant John Russell. (File photo)
A US army sergeant accused of killing four soldiers and a navy officer has been found guilty of premeditated murder, a charge carrying a mandatory life sentence.
Army Sergeant John Russell was found guilty of the crime during a military court session at Joint Base Lewis-McChord in the US state of Washington on Monday.
On April 22, Russell confessed to the Camp Liberty killings, convincing Judge David Conn in issuing a life sentence instead of the death penalty - the maximum punishment for such crimes.
“I just did it out of rage, sir,” Russell told the judge, adding that “What I remember most was I just wanted to kill myself. One hundred percent, I had decided to kill myself.”
The shooting, in which five American troops were killed and three others wounded, took place in May 2009 after the 44-year-old soldier was admitted to the mental health facilities in the US base in Baghdad during the Iraq War.
Two medical evaluations revealed that Russell suffered from severe depression with psychotic features and chronic Post Traumatic Stress Disorder (PTSD), after having served nearly three tours.
The incident marks the largest mass killing by a service member during the Iraq War.
In 2012, the Veterans Administration revealed that nearly 30 percent of its patients who had fought in Iraq and Afghanistan had PTSD.
The suicide rate for American troops has also increased over the past decade to average nearly one a day, prompting then former-Defense Secretary Leon Panetta in 2012 to declare it an epidemic.