Hopkins — also known as Johnny Horton Jr. — was arrested on felony charges of being in possession of firearms and ammunition, according to a statement from the FBI's Albuquerque field office. Hopkins is a member of a group known as the United Constitutional Patriots. The group posted a video last week showing migrants being held before being turned over to US Border Patrol.
"This is a dangerous felon who should not have weapons around children and families," Balderas said. "Today's arrest by the FBI indicates clearly that the rule of law should be in the hands of trained law enforcement officials, not armed vigilantes."
The footage prompted a condemnation from the American Civil Liberties Union of New Mexico, who called it an act of 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.
READ MORE: Militia Arresting Migrants at US-Mexico Border; Why Joe is a No Go
The situation on the US southern border escalated last fall, when a caravan which included thousands of people from Central American countries reached the US. The border guards, however, managed to block migrants trying to cross the border. In March, Trump declared a national emergency in the country to free up to $8 billion in federal funding to maintain border security, including building a wall on the US-Mexico border, stressing that the wall is needed in order to prevent criminals and drugs from pouring into the US.