Oregon police arrested him in 2006 on charges of impersonating a police officer and a felony weapons offense. They had found him showing guns to teenagers in a gas-station parking lot while wearing a police-style uniform and a badge emblazoned with the words “Special Agent.”

Hopkins pleaded guilty in 1996 in Michigan to felony possession of a loaded firearm and was sentenced to 16 months to two years in prison. Officials in South Dakota indicted Hopkins in 2009 on charges of failure to pay child support.

Hopkins finally came under the scrutiny of federal authorities in 2017, after the FBI received reports that his group was “training” to assassinate Barack Obama, Hillary Clinton and George Soros, according to court documents unsealed Monday.

Hopkins, 69, appeared in U.S. District Court on Monday after his arrest over the weekend on yet another charge: being a felon in possession of firearms and ammunition.

The arrest followed the posting online of videos by Hopkins’ group, the United Constitutional Patriots, showing men in camouflage detaining hundreds of migrants in the desert near Sunland Park, New Mexico, and then handing the migrants over to Border Patrol.

In an affidavit, David S. Gabriel, an FBI special agent, said the bureau was made aware of the activities of Hopkins after receiving reports in October 2017 of “alleged militia extremist activity” in northwestern New Mexico.

Gabriel said two FBI agents went to a trailer park in Flora Vista, New Mexico, where Hopkins was living. The agents entered the home and saw about 10 firearms in plain view.

The court affidavit gave few details about the report the FBI received stating that the United Constitutional Patriots “were training to assassinate George Soros, Hillary Clinton, and Barack Obama because of these individuals’ support of Antifa.” The term Antifa refers to left-wing activists who have clashed with right-wing groups in cities across the country.

Hopkins’ lawyer, Kelly O’Connell, disputed the reports about assassination plans.

O’Connell said Hopkins planned to plead not guilty to the latest charge.

This article originally appeared in The New York Times.