David “Chris” Maland, the Border Patrol agent killed Monday, was shot while conducting a traffic stop in a Vermont town near the Canadian border, according to the FBI’s latest update on the case.

The federal officer killed while on duty near the Canadian border has been identified as a U.S. Air Force veteran who provided security at the Pentagon during the Sept. 11 attacks.

The FBI is investigating a Border Patrol agent–involved shooting, according to a statement from the Vermont State Police.