An Army judge ordered the hypnosis for Sergeant John Russell, 48, in granting three defence motions aimed at learning more about Russell's mental state during a shooting frenzy the military has said might have been triggered by combat stress.
Russell, a member of the Army's 54th Engineer Battalion based in Bamberg, Germany, faces five charges of premeditated murder, one charge of aggravated assault and one charge of attempted murder in connection with the May 2009 shootings.
Two of the dead were medical staff officers at a combat stress counseling clinic called Camp Liberty, part of the US military's Victory Base Complex near the Baghdad airport. The other three were soldiers who happened to be at the center at the time.
A forensic psychiatrist who has since examined Russell suggested the sergeant was "provoked to violence by the ineptitude and lack of compassion" he experienced from clinic staff when he sought treatment for depression several days before the shooting.
The judge in the case, Army Colonel David Conn, cited the psychiatric opinion verbatim in his defense motions ruling, made public on Tuesday.
In addition to assigning a Stanford University specialist to interview Russell under hypnosis, Conn ordered a sophisticated brain scan and battery of psychological tests for the sergeant.
Accused gunman had sought treatment
Six months ago, Russell was ordered to stand trial in a military court at Joint Base Lewis-McChord near Tacoma, Washington. The court-martial could begin as early as March.
But his defense team is seeking to show that Russell was not in control of his actions and thus not criminally responsible.
During proceedings last month on his mental condition, a University of Pennsylvania forensic psychiatrist said he concluded that Russell was suffering from post-traumatic stress disorder and psychosis at the time of the shooting spree.
The psychiatrist, Dr. Robert Sadoff, also said Russell suffered from "dissociative disorder," or a lack of memory about the shootings.
Moreover, Saddoff harshly criticised a psychologist and a psychiatrist on the staff at Camp Victory for what he called "inexcusable treatment" of Russell days before the shooting.
"I have never seen a case such as this one where the defendant was provoked to violence by the ineptitude and lack of compassion of two of my colleagues, who were assigned to evaluate and treat Sergeant Russell while he was in an acute state of depression, with suicidal intent, while on active duty in Iraq," Sadoff wrote in a submission quoted in Conn's ruling.
Russell's lawyer, James Culp, said his client had been "abused" and belittled by the two officers, and that one had chased Russell out of the clinic while screaming at him. They were not the officers killed in the shooting rampage.
Culp told Reuters he hoped to prove that his client was legally insane at the time of the shootings.
"The defense and prosecution agree that Sergeant Russell was psychotic," Culp said. "The question is, 'How psychotic was he?'" He added: "Not one person in the military has ever been found not guilty by reason of insanity."
The case comes at a sensitive time for the Army, which is in the process of deciding how to prosecute Staff Sergeant Robert Bales, a soldier accused of killing 16 Afghan villagers in cold blood earlier this year.
Culp has said Russell was at a breaking point from the stress of multiple deployments, and suffered "at least one traumatic experience involving civilian casualties" and "mass grave sites" while serving in Bosnia and Kosovo.