Maine's two senators are requesting the Army's inspector general investigate the deadly shooting there by a member of the Army Reserve two weeks ago that killed 18 people.

The lawmakers, Sens. Susan Collins, a Republican, and Angus King, an Independent, want to know whether the service followed policy and whether any reforms are necessary after the massacre in Lewiston, the latest mass shooting to grab the national spotlight.

The killer, Robert Card, was a sergeant first class in the Army Reserve. He was admitted to the Keller Army Community Hospital at West Point, New York, on July 15 after his erratic behavior sparked concerns in his unit during a training event. Before that, his family told authorities on several occasions going back to January about his deteriorating mental health.

"Despite these warning signs, and others, there was no attempt to trigger the crisis intervention laws in New York (where Mr. Card was training and hospitalized) or Maine (where Mr. Card resided)," Collins and King wrote in a joint letter shared Monday on X.

Everyone who knew Robert Card was concerned about his behavior. His ex-wife and teenage son. His siblings, parents and friends. Fellow members of an Army Reserve unit in Saco, Maine.

They knew he was having psychotic episodes and hearing voices. They knew he had been making threats and that those threats were getting more specific. They knew he had several guns and knew how to use them.

Many spoke up.

Local police were alerted in May and again in September about his increasingly erratic behavior. In between those contacts, Card spent two weeks at a New York psychiatric facility at the urging of commanding officers.

The warning signs before Card shot and killed 18 people on Oct. 25 in Lewiston were glaring and abundant, and still, he was not stopped before he carried out the worst massacre in Maine's history and then took his own life. The drip, drip, drip of information that has come out since suggests Card's mental health deteriorated rapidly early this year and may have coincided with or been triggered by a bad breakup and his first hearing aids.

But significant gaps in the timeline remain -- the biggest being from Sept. 17, when a Sagadahoc County Sheriff's deputy tried unsuccessfully to visit Card at his Bowdoin home, to Oct. 25, when the shootings occurred.

Family members told police Card distanced himself from them in the month before the shootings and wasn't responding to messages or visits to his home. They have so far declined to speak with Portland Press Herald/Maine Sunday Telegram reporters or failed to return messages. If others encountered Card more recently, they haven't come forward.

In the days since the tragedy, scrutiny has intensified over whether enough people took Card's behavior and threats seriously and whether enough was done to intervene. Gov. Janet Mills acknowledged this Wednesday when she launched an independent commission that will look into the shootings and police response that followed, as well as the months before.

"It is important to recognize that, from what we know thus far, on multiple occasions over the last 10 months, concerns about Mr. Card's mental health and his behavior were brought to the attention of his Army National Reserve unit, as well as law enforcement agencies here in Maine and in New York," Mills said. "This raises crucial questions about actions taken and what more could have been done to prevent this tragedy from occurring."