Updated

A Las Vegas anti-government extremist has been sentenced to 18 months in prison for possession of an unregistered machine gun.

Federal prosecutors say Harold Call was sentenced Tuesday, despite the 68-year-old's attempt to withdraw his plea and fire his lawyer.

Call is one of four anti-government, anti-tax-movement followers arrested in 2009 after a three-year FBI investigation into a group who believed they were separate from the United States. Agents say they held seminars teaching followers how to avoid taxes.

U.S. District Judge Kent Dawson says Call was his own worst enemy, filing frivolous documents the judge described as "stuff from outer space." He must surrender to prison officials by Dec. 1.

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Information from: Las Vegas Review-Journal, http://www.lvrj.com