The rapid expansion of U.S. Immigration and Customs Enforcement under President Donald Trump's immigration crackdown is facing renewed scrutiny after family members of an officer involved in a fatal shooting said he had long struggled with serious mental health issues and should never have been hired.

The concerns center on David Brouillette, the ICE officer who fatally shot a Colombian man in Maine this week.

Relatives told The Associated Press (AP) that Brouillette had experienced significant mental health challenges since childhood, prompting fresh questions about whether the agency's hiring and screening procedures are keeping pace with its aggressive recruitment campaign.

The Trump administration has made expanding ICE a cornerstone of its immigration enforcement strategy, with Congress providing billions of dollars to dramatically increase staffing.

While the Department of Homeland Security has defended the agency's recruitment process as rigorous, critics argue the rapid hiring effort risks allowing unsuitable candidates into law enforcement positions.