AUBURN (WGME) – Investigators say the Lewiston mass shooting suspect tried to get a suppressor, also called a silencer, but was stopped from doing so in August.

The ATF confirmed to CBS13 that the suspect tried to buy a so-called silencer but was denied because of a mental health question just a few months before the mass shooting.

The bureau wouldn’t confirm where, but the New York Times reports it happened at Coastal Defense in Auburn.

The Lewiston mass shooting suspect went to Coastal Defense Firearms on Aug. 5, according to the New York Times.

The paper reports he bought a suppressor, also known as a silencer, from another store, which then sent it to Coastal Defense for pick-up.

“This guy was a firearms expert, the shooter. And he knew what he was doing. And he was obviously trying to acquire a suppressor for something,” University of New Haven Criminal Justice Associate Professor Mike Lawlor said.

Lawlor says in most states, it’s legal to purchase and have one, but under federal law you need a permit.

“It’s not simple like walking into a store and buying one,” Lawlor said.

Rick LaChapelle, the new Lewiston City Council President and majority owner for Coastal Defense, told the Times that when the Bowdoin man came in, he completed an ATF Form 4473. In it, the suspect said yes, he had been committed to a mental institution, according to the ATF.

“It would then have been a violation of federal law for that dealer to transfer a suppressor to him,” Lawlor said.

LaChapelle reportedly said staff didn’t give the man the device. The suspect said he would get his attorney involved and come back but never did.

CBS13 Reporter Mal Meyer: “At that point, should staff members have escalated this further to another law enforcement agency or something like that?”

Lawlor: “They’re not obligated to, but you would think that that would be an indication that there might be a serious problem here.”

An ATF spokesperson says he wasn’t aware of the store contacting the bureau about this.

CBS13 repeatedly reached out to LaChapelle for comment but didn’t get a response.

Maine State Police says they weren’t notified and were not involved in this process.

CBS13 also contacted the Auburn Police Department for comment. We have yet to hear back from them.