Mr. Thompson, the 50-year-old chief executive of UnitedHealthcare, the largest US health insurer, was shot dead outside a Manhattan hotel in the early evening of December 4, sparking a massive manhunt for the killer.
Mr. Mangione, 26, was arrested days later in Pennsylvania and taken to New York, where he faces both federal and state charges, including first-degree murder in furtherance of terrorism.
Investigators accuse him of targeted killing, pointing to evidence of a long-standing animosity toward the U.S. health care industry. On social media, support for Mr. Mangione was often accompanied by insults and complaints about the health insurance sector.
“For some time we have been concerned about the rhetoric on social media,” Mayorkas said on Sunday. “We have seen narratives of hate. We have seen stories of anti-government sentiment. We saw personal grievances in the language of violence.”
Mayorkas, whose Department of Homeland Security is partly responsible for protecting Americans from domestic terrorism, said his department sees a “wide range of narratives” that “drive some people to violence.”
“That’s something we’re very concerned about,” he said. “This is a high-risk environment.”
But the 65-year-old, whose time at the helm of the department ends next month, stressed that Mr Thompson’s killing was “the act of an individual (and) does not reflect the American public”.
