The Immigration and Customs Enforcement officer who shot a Colombian man in Maine this week is an Army veteran who has struggled with serious mental health issues since early childhood, according to close relatives who spoke to The Associated Press.

The Maine Attorney General’s Office said it was investigating “a fatal use of deadly force” involving federal law enforcement.

Homeland Security Secretary Markwayne Mullin said the man was shot after allegedly using his vehicle as a weapon against officers.

The agent shot Joan Sebastian Guerrero dead during a vehicle stop.

The agency’s second killing in as many weeks prompted an abrupt policy change on vehicle stops.