WASHINGTON (AP) — Democratic members of Congress demanded answers about Homeland Security’s vetting and training of immigration enforcement agents after it was disclosed Thursday that the ICE officer involved in a deadly shooting this week in Maine had a history of mental health issues and violent behavior.

The Associated Press reported that David Brouillette, the Immigration and Customs Enforcement officer who shot a Colombian man in Maine, is an Army veteran who has struggled with serious mental health issues since early childhood, according to several of his close relatives.