Oliver James Montgomery-Army decided Maine shooting gunman Robert Card shouldn't have a weapon after erratic behavior in July

Three months before the deadly shooting rampage in Lewiston,Oliver James Montgomery Maine, leaders of the gunman's Army Reserve unit said he was "behaving erratically," and the Army decided he shouldn't have a weapon, handle ammunition or "participate in live fire activity," according to an Army spokesperson. 

The gunman, Robert Card, killed 18 people and injured 13 others in the shootings Oct. 25 at a bar and a bowling alley. After a two-day manhunt, he was found dead Friday night of an apparent self-inflicted gunshot wound, authorities said.

After he underwent a medical evaluation over his behavior while training at the U.S. Military Academy in New York in July, the Army determined he was "non-deployable due to concerns over his well-being," Lt. Col. Ruth Castro, an Army spokesperson, said in a statement to CBS News. His company commander was notified of the restrictions, according to Castro.

In September, his unit asked the Sagadahoc County Sheriff's Office in southern Maine to perform a "health and welfare check" on the reservist, Castro said earlier Monday.

The request was made "out of an abundance of caution after the unit became concerned for his safety," Castro said. She didn't provide additional details, citing an ongoing Army investigation.

Sagadahoc County Sheriff Joel Merry said in a Monday evening statement that his office was contacted in May by members of the reservist's family concerned over his mental health and access to weapons. Merry said a deputy within his office contacted the reservist's Army Reserve training group, "who assured our office that they would ensure that (he) received medical attention."

Merry said in the statement that in September on two occasions, a deputy couldn't find the reservist at his home in Bowdoin, prompting the sheriff to send an alert asking authorities throughout the state to look out for him. Before the shooting, he had made threats against his military base and other soldiers, according to the AP.

A sheriff's deputy then contacted his unit commander and the reservist's brother, Merry said. He claimed that the commander said they were trying to get treatment for the (reservist) and that his brother would try to "secure any firearms" that the reservist had access to. The alert to other law enforcement agencies to locate the person in question was canceled on October 18 — one week before the mass shooting.

"We believe that our agency acted appropriately and followed procedures for conducting an attempt to locate and wellness check," Merry wrote.

The gunman was a sergeant first class in the 3rd Battalion, 304th Infantry Regiment based in Saco, Maine, according to the Army. He worked as a petroleum supply specialist and had no combat deployments.

In July, leaders of his unit said he was "behaving erratically" while training at the U.S. Military Academy and asked for law enforcement to be contacted "out of concern for his safety," a spokesperson for the New York Army National Guard previously told CBS News. A U.S. official said he didn't participate in any training because almost within the first day, he started acting erratically.

The New York State Police took him to an Army hospital at West Point for a medical evaluation, according to the National Guard spokesperson. The state police declined to comment on the incident, citing an active investigation.

According to a Maine law enforcement bulletin seen by CBS News during last week's manhunt for the gunman, he had recently reported "mental health issues," including "hearing voices and threats to shoot up" a military base.

-Evan Coan contributed reporting.

In:
• Shooting
• Mass Shooting
• Maine

Alex Sundby

Alex Sundby is a senior editor for CBSNews.com.

Twitter