One year after Army reservist Robert Card fatally shot 18 people and wounded 13 others in Lewiston, Maine, his family members are working to bring awareness to traumatic brain injuries.

Card, a firearms and hand grenade instructor, had documented mental health problems before he opened fire on a bowling alley and a bar and grill using a Ruger SFAR on Oct. 25, 2023. Authorities located him two days later with a self-inflicted gunshot wound to the head.

"We want to make sure this doesn't ever, ever happen again to another family." Nicole Herling, Card's sister, told NBC News in an interview published Tuesday.

Herling and her husband James have spoken publicly about their family's efforts to flag Card's mental illness prior to the massacre, which was Maine's deadliest mass shooting.

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Independent commission on Robert Card

Members of the independent commission investigating the law enforcement response to the mass shooting in Lewiston, Maine, listen as Nicole Herling, bottom left, sister of shooter Robert Card, testifies on Thursday, May 16, 2024, in Augusta, Maine. (AP Photo/Robert F. Bukaty, File)

Family members tried to call a veterans' crisis hotline, as well as Card's military base, to get help.

A month before the massacre, local law enforcement even responded to Card's residence after receiving reports from his family, but officers did not make contact, according to NBC.

A fellow Army reservist even told his superiors on Sept. 15 that he thought Card was "going to snap and do a mass shooting," according to testimony from Card's family during a hearing before Maine's legislature in May as part of an independent investigation into the mass shooting.

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James Herling

James Herling pauses his testimony while recalling the moment he realized the shooter was his brother-in-law, Robert Card, while testifying on Thursday, May 16, 2024 in Augusta, Maine, during a hearing of the independent commission investigating the law enforcement response to the mass shooting in Lewiston, Maine. (AP Photo/Robert F. Bukaty)

Researchers studied Card's brain after the shooting and determined that he had severe traumatic brain injuries.

His family said during the May hearing that researchers told them it was "one of the worst" cases of traumatic brain injuries they had seen, with Card potentially being exposed to thousands of explosions over the course of his career as a hand-grenade instructor, according to NBC.

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Robert Card with NY state police

In this image taken from New York State Police body camera video that was obtained by WMTW-TV 8 in Portland, Maine, New York State Police interview Army reservist Robert Card, the man responsible for Maine's deadliest mass shooting, at Camp Smith in Cortlandt, New York, on July 16, 2023. (WMTW-TV 8/New York State Police via AP, File)

The Herlings are working on starting a nonprofit organization, called Rising Over Brokenness, to educate the public on the dangers of brain injuries.

"We had recognized that we needed to help other families, especially once we realized that Robbie's brain had been compromised," James Herling told NBC anchor Lester Holt.

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Lewiston, Maine shooting victims memorial

Rain-soaked memorials for those who died in a mass shooting sit along the roadside by Schemengees Bar & Grille on Oct. 30, 2023 in Lewiston, Maine. (AP Photo/Matt York, File)

The Herlings have also listed the names of all 18 victims of the shooting on the walls of their home. They also have all 18 names lining their property with blue hearts, according to NBC.

"I don't ever want to talk about Robbie without acknowledging the pain that he's caused to other people," Nicole Herling said.

MAINE AUTHORITIES THOUGHT CONFRONTING ROBERT CARD WOULD INFLAME SITUATION IN WEEKS BEFORE SHOOTING: VIDEO

Maine-Shooting

Crime scene tape still surrounds Schemengees Bar & Grille, Oct. 29, 2023 in Lewiston, Maine. (AP Photo/Matt York)

The U.S. Department of Defense (DOD) in August announced a Warfighter Brain Health Initiative that will focus on "identifying and implementing best practices to promote overall brain health and countering traumatic brain injury, including efforts to mitigate blast overpressure risks for service members."

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On Oct. 15, the families of 100 survivors and victims of the Oct. 25, 2023 mass shooting served a legal notice expressing their intent to sue the DOD, Army and Keller Army Community Hospital for "negligence in failing to respond to warning signs and an explicit threat to commit a mass shooting, from Army Reserve Sergeant Robert Card," according to attorney Travis Brennan.