(CNN) Militia leader Larry Mitchell Hopkins should remain behind bars pending his trial on a federal weapons charge, a judge ruled Monday.

US Magistrate Judge Karen B. Mozen ordered that Hopkins remain detained because "clear and convincing evidence" indicated "no condition or combination of conditions of release will reasonably assure the safety of any other person and the community." The judge listed a number of additional factors as reasons for her decision, including Hopkins' use of aliases, his criminal history, his prior failure to appear in court as ordered, his probation violations and his association with the United Constitutional Patriots militia group.

Hopkins is charged with being a felon in possession of firearms and ammunition. He pleaded not guilty at a hearing in Albuquerque, New Mexico, on Monday and requested release from custody, according to court records. The judge denied that request.

Monday's hearing was delayed after authorities evacuated the courthouse for a time because of what the US Marshals Service later described as a safety issue.

"The FBI and US Marshals Service are continuing to investigate the matter," said Joy Josephson, spokeswoman for the Marshals Service.