Community members gather on Nov. 2 during a candlelight vigil in Auburn after the Lewiston mass shooting on Oct. 25. Matt York/Associated Press

Maine’s congressional delegation has signed a letter requesting an independent review of the Defense Department’s efforts to protect military personnel from blast exposure-related brain injuries.

The request for a review by the U.S. Government Accountability Office comes follows a determination that the Army reservist responsible for the Lewiston mass shooting in October had likely suffered brain injuries from exposure to repeated blasts during training, and that it likely contributed to his declining mental health and behavioral changes before the tragedy.

Signing the letter were independent U.S. Sen. Angus King, Republican Sen. Susan Collins and Democratic U.S Reps. Chellie Pingree and Jared Golden. In all, 23 lawmakers signed the letter, which is partly in response to a brain tissue analysis of Lewiston shooter Robert Card.

Card killed 18 people and wounded 13 during a shooting rampage before he died from a self-inflicted gunshot wound. The brain tissue analysis conducted by Boston University, released in March, concluded that injuries Card suffered during training likely played a role in his declining mental health before the shooting. Card, an Army reservist, was “exposed to thousands of low-level blasts” during years of grenade training in New York state, according to personnel records.

The Defense Department is reviewing its training protocols to help reduce exposure to blast overpressure, but the lawmakers said they’re concerned that those efforts aren’t going far enough. They are recommending the GAO step in and review the Defense Department’s response.

“Major gaps remain in turning this research into action to better protect service members’ brain health, particularly to mitigate the impact of blast exposure and overpressure on service members,” according to the letter. “The (Defense) Department needs to take more urgent action to mitigate blast overpressure and support service members. Otherwise, troops will continue to struggle to get the care they need and deserve.”

Maine’s congressional delegation also signed onto a bill – the Blast Overpressure Safety Act – this spring that would require the military to monitor service members’ blast exposures during training, and to routinely perform neurocognitive tests to look for possible brain injuries.

Card exhibited erratic and disturbing behavior in the months before the shooting, resulting in a two-week psychiatric hospitalization in New York state in July 2023.