The ICE agent who killed an immigrant in Maine has a documented history of violence and mental illness, raising alarm about who the agency is hiring and how little it seems to vet them.

• The agent, David Briette, was named after killing a Colombian man during a vehicle stop; his ex-wives and relatives went public calling him violent and mentally unstable.
• Court records show past abuse of his wives and daughter, death threats, a bipolar diagnosis, and brain injury with memory problems — yet ICE handed him a gun.
• The victim wasn't even the person ICE meant to stop, and the agent's body camera was off, leaving only his word that the man tried to run him over.
• A similar Houston killing involved an unmarked car; the family thought it was a carjacking, and Tom Homan admitted on TV he hadn't seen the video and that lights may not have been used.
• Assault-on-ICE cases are collapsing in court — of 558 people charged, only four were convicted, with many cases showing agents made up or provoked the incidents.

Outlook: If Democrats take the House, expect investigations into ICE hiring and a growing push to overhaul or abolish the agency.