A federal judge in Minneapolis has refused to release from jail a National Guardsman and member of a militia organization from Maplewood who was arrested last month and charged with stealing the names and Social Security numbers of Army members as part of an identity theft scheme.

In a ruling released Thursday, Keith M. Novak, 25, must remain incarcerated pending trial because “clear and convincing” evidence shows that “no condition or combination of conditions of release will reasonably assure” the public’s safety should the defendant be released pending trial. The evidence was equally compelling, the court added, that Novak also would present a flight risk if temporarily freed.

According to a source who has knowledge of both cases, there is a “high probability” that Novak was implicated by militia group member Buford “Bucky” Rogers, of Montevideo, Minn., when Rogers told an FBI agent that he knew a man named Keith who was involved in intelligence work for the National Guard and was also involved in militia activity.

The source added that Novak had his security clearance removed last summer when he was under investigation. The FBI has made no statement that the two men are linked. Both men, however, are alleged by the FBI to have spoken of bombing government facilities, although neither has been charged with such a crime.

Rogers, a member of a small group called the Black Snake Militia, planned an attack on a police station and National Guard facility and the bombing of a radio tower, all in Montevideo, the FBI alleged at the time of his arrest. He was indicted on charges of possessing illegal explosives and a firearm.

An FBI agent testified Monday that Novak belonged to the 44th Spatha Libertas, or “Sword of Freedom,” militia and had discussed bombing a National Security Agency facility in Utah, although he has not been charged with that. He was described in court documents as a “human intelligence collector” for the Minnesota Army National Guard and an “intelligence analyst” when he was a member of the Army’s 82nd Airborne Division.