(CNN) 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.

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