WASHINGTON– Democratic members of Congress demanded answers about the Department of Homeland Security’s vetting and training of immigration agents after it was revealed 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.

The AP contacted congressional leaders and several key lawmakers from both parties for a response.

The top Democrat on the House Homeland Security Committee, Rep. Bennie Thompson of Mississippi, said Brouillette’s history of violence and mental health issues, as well as the death in Maine, “call directly into question the alleged vetting and training that ICE conducts on its recruits.”

“This senseless tragedy must be investigated and the officer responsible must be taken off our streets and face justice for his actions,” Thompson said in a statement to the AP.

Senate Democratic Leader Chuck Schumer, who led the shutdown of the Department of Homeland Security earlier this year as Democrats sought to impose restrictions on immigration enforcement operations, said the consequences of failing to put up barriers to ICE are now measured in lives.

“The Trump administration sent 12,000 officers onto our streets without ensuring they were fit to carry a badge and carry a gun, and Republicans gave this rogue agency huge power and no accountability,” Schumer said in a statement. “They gave power to ICE. Now they must work with us to prevent more murders.”

The report on Brouillette’s disturbing past comes as the Department of Homeland Security has been on a hiring spree, fueled by huge sums of money from Republicans in Congress to help carry out President Donald Trump’s mass deportation agenda. It raises new questions about the department’s efforts to hire, vet, train and quickly deploy recruits who are being sent to patrol communities across the United States.

Sen. Susan Collins of Maine, the Republican chairwoman of the powerful Appropriations Committee, referred to her earlier statement that “an impartial investigation into the Biddeford shooting is necessary as the details surrounding this tragedy are important.”

Collins had previously said it was “extremely unfortunate” that the officer did not have a body camera.

The senator secured $20 million to expand the use of body cameras and $2 million for de-escalation training as part of the Homeland Security funding bill that Republicans passed to end the department’s shutdown.

“The Democratic government shutdown delayed the enactment and implementation of these important safety measures,” he said.

At least 10 people have died in encounters with immigration agents since Trump launched the crackdown after taking office, including Johan Sebastián Durán Guerrero, 25, a Colombian national who was shot and killed by Brouillette on Monday while he was in his car near his home in the coastal town of Biddeford, Maine.

“This bomb is absolutely horrific — exactly the intolerable danger we feared as a result of arrest quotas and inadequate training,” Sen. Richard Blumenthal, D-Conn., said in a statement to the AP.

“This agent clearly should have never had a gun, much less one provided to him by the United States government. And now a man is dead. I will continue to demand answers and accountability,” he said.

Sen. Alex Padilla, D-Calif., said Trump and his administration “have encouraged ICE and CBP to come in and terrorize our communities, even if those agents are untrained, inadequately vetted or inexperienced,” referring to Customs and Border Protection.

“The murder of Johan Sebastián Durán Guerrero was horrific,” he said in a statement to the AP, “and there must be a credible, independent and transparent investigation to hold those responsible accountable.”