A Navy SEAL commander was charged on Tuesday with failing to act against Special Operations Chief Edward Gallagher, a decorated US medic and sniper currently under investigation for committing war crimes in Iraq in 2017.

Platoon commander Lieutenant Jacob Portier is facing seven charges under the Uniform Code of Military Justice, including “dereliction of duty”, after reportedly being made aware of extrajudicial executions committed by Gallagher, but failing to report the incidents.

After his latest tour fighting Daesh in Iraq, Gallagher had been named the top platoon leader in SEAL Team 7 and nominated for the Silver Star, the military’s third-highest honour. Yet a different picture was painted at a two-day hearing last week, where prosecutors presented testimonies from Gallagher’s colleagues who described his behaviour during his deployment last year as reckless and bloodthirsty.

A veteran of seven previous operations in Iraq and Afghanistan, Gallagher reportedly fired into civilian crowds, gunned down an Iraqi girl walking along a riverbank and an old man carrying a water jug, threatening to kill fellow SEALs if they reported his actions.

“Every single sniper in the platoon said he was not a good sniper,” Special Agent Joe Warpinski of the Naval Criminal Investigative Service told the military court.

Some fellow officers were reportedly so fearful of Gallagher’s behaviour that they even tried to tamper with his sniper rifle to make it less accurate, and developed a habit of firing warning shots to scare away Iraqi civilians so the chief would not have a chance to shoot them.

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The 39-year-old officer is also accused of killing a fighter, who was aged between 12 and 17, who had been captured and wounded by Iraqi forces in Mosul. Navy investigators said that one SEAL medic was kneeling over the fighter’s head, treating him, when Gallagher walked up and, without saying a word, took out a handmade knife and stabbed the teenager several times in the neck and side.

Members of the platoon then posed for photos with Gallagher as he held the teenager’s head up by the hair with one hand, and held his knife in the other. He reportedly later sent the photo to a colleague with the message: “I got him with my hunting knife.”

Lieutenant Portier is accused of having known about the incident and not taking action against the US army chief. In April this year a criminal investigation was finally opened after some officers reported the execution to senior leadership.

If found guilty, Gallagher could serve a life sentence for obstruction of justice, premeditated murder, attempted murder, drug possession and almost 12 other offenses, including “bringing discredit upon the armed forces”.

Gallagher’s defence team have dismissed the accusations as lies invented by the accused’s colleagues out of jealousy.

On the photos taken alongside the dead Mosul teenager, lawyer Phillip Stackhouse told the court that posing with the corpses was a common feature of many US military expeditions: “These types of pictures are not unique; they’ve been in every Iraq case I’ve ever done.”

In September, after prosecutors complained to the Navy of efforts being made by Gallagher to intimidate witnesses, the chief was arrested and put in pre-trial confinement, where he remains awaiting further procedures.

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