WASHINGTON — 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.

The AP reached out to congressional leaders and several key lawmakers of both parties for 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, “directly call into question the supposed vetting and training ICE does of its recruits.”

“This senseless tragedy must be investigated and the officer responsible should 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 a shutdown of the Department of Homeland Security earlier this year as Democrats tried to impose restraints on immigration enforcement operations, said the consequences of failing to put guardrails on ICE are now being measured in lives.

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

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

Sen. Susan Collins of Maine, the Republican chair of the powerful Appropriations Committee, referred back to her prior statement that “an impartial investigation into the shooting in Biddeford needs to proceed, as the details surrounding this tragedy are important.”

Collins had said earlier that it is “extremely unfortunate” that the agent did not have a body-worn camera.

The senator ensured $20 million for expanded use of body-worn cameras and $2 million for deescalation training as part of the Homeland Security funding bill that Republicans approved to end the department shutdown.

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

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

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

“This agent clearly should never have had a gun — let alone one provided to him by the United States government. And now a man is dead. I’m going to continue demanding answers and accountability,” he said.

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

“The killing of Johan Sebastián Durán Guerrero was horrifying,” he said in a statement to the AP, “and there must be a credible, independent, and transparent investigation so that those responsible are held accountable.”