In emotional testimony Thursday morning, family members of Robert Card, the man responsible for two shootings that left 18 people dead in Lewiston, Maine, testified before the independent commission formed to investigate the October 25, 2023, mass shootings.

“If you were to ask me what one thing I would like for the commission to find and point out, it would be ultimately to get to the root cause of this tragedy. We can point fingers at who’s at fault, who has failed to make the ultimate contact, but in all reality, we all could have done better — from the sheriff’s office to the Army to the family,” said James Herling, Card’s brother-in-law.

Documents shared with CNN by the Sagadahoc County Sheriff’s Office showed Card’s family had called the department as far back as May 2023, voicing concerns over his well-being and access to firearms. The US Army previously told CNN a health and wellness check was requested by the shooter’s unit “out of an abundance of caution after the unit became concerned for his safety.” An independent review last year concluded the sheriff’s office acted “reasonably” but recommended improvements to the department’s strategy.

Card, a US Army reservist and certified firearms instructor, went on two shooting rampages at a bar and bowling alley in Lewiston, killing 18 people and wounding 13 others with an assault rifle. After a 48-hour manhunt following the shootings, Card was found dead from a self-inflicted gunshot wound to the head near a river some 10 miles from Lewiston.

The Concussion Legacy Foundation said in March that tissue samples from Card’s brain showed evidence of traumatic brain injury and suggested he had been exposed to “thousands of low-level blasts” during his time at an Army hand grenade training range.

“I am hoping that this commission will find that the DOD needs to enhance the protection of our soldiers because when they release them as civilians, they are releasing them without proper care,” Herling said. “This is not an excuse for the behavior and action that Robbie committed. It was a wrongful act of evil. My brother-in-law was not this man. His brain was hijacked.”

Nicole Herling, Card’s sister, testified about the “significant challenge” to contact Card’s chain of command in the Army for help when he began showing signs of mental illness.

“The Department of Defense’s negligence regarding traumatic brain injury must be addressed, and they must be held accountable for change,” Nicole Herling said.

“It’s important to acknowledge that Robbie’s decline involved other factors, and I’m not here to excuse his behavior,” she added. “If we appeared silent, it wasn’t because we lacked empathy. We were in shock and disbelief, unable to comprehend that Robbie was capable of such horror.”

CNN has reached out to the Department of Defense for comment.