LEWISTON, Maine (AP) — Two senators from Maine asked the U.S. Army inspector general on Monday to provide a full accounting of interactions with a reservist before he killed 18 people and injured 13 others in the deadliest shooting in the state’s history.

U.S. Sens. Susan Collins, a Republican, and Angus King, an independent, told Lt. Gen. Donna W. Martin in a letter that it’s important to understand “what occurred, or failed to occur” at the federal level, including the Army, before Robert Card opened fire at a bowling alley and bar in Lewiston.

Fellow soldiers expressed concerns about Card’s mental health before the Oct. 25 shootings. One of them sent a text message in September saying, “I believe he’s going to snap and do a mass shooting,” according to law enforcement.

The senators view their federal request as working in tandem with an independent commission that Democratic Gov. Janet Mills is convening to explore the facts related to the shooting, including the police response.

“As we continue to grieve the needless loss of life that day, we must work to fully understand what happened — and what could have been done differently that might have prevented this tragedy — on the local, state, and federal levels,” the senators wrote.

The senators posed several questions including under what circumstances the Army reports personnel to the National Instant Criminal Background Check System, and when the Army seeks to invoke state laws to temporarily remove firearms from a soldier’s possession.

Concerns over Card’s mental health during military training led to a 14-day hospitalization at the Four Winds Psychiatric Hospital in Katonah, New York, last summer. The worries continued after Card returned home to Maine.

A deputy visited Card’s Bowdoin home twice, once with an additional deputy for backup, to perform a wellness check in September but Card never came to the door, officials said. What happened after that is unclear. The sheriff’s office canceled its statewide alert seeking help locating Card a week before the killings.