A leader of an armed militia that has held hundreds of migrants at the border previously claimed the group was training to assassinate Hillary Clinton and Barack Obama, according to court documents unsealed on Monday.
FBI agents visited Larry Mitchell Hopkins' Flora Vista, New Mexico, residence in November 2017 after learning of the alleged statement. Witnesses also reported seeing members of the militia with firearms at the home, the probable cause statement said.
The FBI recovered nine weapons and ammunition during the search, according to court papers.
The 69-year-old Hopkins -- who is also known as Johnny Horton Jr. -- was charged Monday with being a felon in possession of firearms and ammunition stemming from the 2017 search, according to a criminal complaint.
Hopkins, who was arrested on Saturday, made his initial court appearance on Monday in a federal courtroom in Las Cruces.
The leader of United Constitutional Patriots was prohibited from possessing firearms or ammunition because he had been previously convicted of at least three felonies then, including criminal impersonation of a peace officer in Oregon in 2006, according to the criminal complaint.
The US Attorney's Office declined to say why Hopkins was charged more than a year after his residence was searched.
Hopkins' attorney Kelly O'Connell told reporters outside the courthouse in New Mexico that his client pleaded not guilty, according to CNN affiliate KTSM.
O'Connell said the guns and ammunition did not belong to Hopkins.
"According to the charges that I read, this is not dealing with what is happening down here," O'Connell said, referring to the militia's presence at the border.
The court document also detailed what witnesses alleged when they contacted the FBI about Hopkins and the militia.
Reports to an FBI tip line in October 2017 alleged "militia extremist activity" in Flora Vista, according to an FBI agent's probable cause statement.
Hopkins was identified as the group's so-called commander and his home was its "base," court papers said.
Witnesses reported seeing about 20 militia members "armed with AK-47 rifles and other firearms" at Hopkins' residence, according to court papers.
"Hopkins also allegedly made the statement that the United Constitutional Patriots were training to assassinate George Soros, Hillary Clinton and Barack Obama, because of these individuals' support of Antifa," according to court papers.
Soros is a billionaire investor and philanthropist.
The court papers didn't say when Hopkins allegedly made the statement.
The armed group had reportedly detained migrants near Sunland Park, New Mexico, federal prosecutors said.
Last week, videos posted online purported to show migrants being held by the militia before being turned over to the US Border Patrol. In the footage, people wearing full military fatigues can be seen with handguns strapped to their sides, wearing gloves and black masks.
The footage has prompted a condemnation from the American Civil Liberties Union of New Mexico, which in a letter likened the militia's actions to kidnapping.
A spokesman for the group previously said their actions were legal, "comparing the detention of the migrants to 'a verbal citizen's arrest,'" according to a report from The New York Times.
Jim Benvie, the spokesman, told the Albuquerque Journal on Monday the militia members are "just a group of volunteer patriots, veterans in law enforcement."
Hopkins was unarmed while living at the camp near the border fence, he told the newspaper. "He didn't have a gun. He didn't bring a gun. Johnny did not bring a gun," he said.
Hopkins is a "Vietnam veteran who was cooking meals for people at the camp. He was a victim in this," Benvie told the paper.
O'Connell told reporters the group believes "they are helping to enforce the laws of America on immigration."
Hopkins faces a maximum sentence of 10 years in jail if convicted. He will remain in custody while he awaits a preliminary hearing set for April 29.
CNN's Dakin Andone, Catherine Shoichet and Chris Boyette contributed to this report.
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