A federal trial is slated to begin this week in Albany, N.Y., for an orthodontist long considered an “elder” in the antigovernment “sovereign citizens” movement and who now faces charges of filing bogus tax returns between 2007 and 2010 in an effort to collect millions in refunds.

Glenn Richard Unger, 62, who often uses the alias “Dr. Sam Kennedy,” is accused of trying to obtain $36 million from the IRS through bogus tax returns. Federal prosecutors have also accused him of scamming another orthodontist, according to the Times Union of Albany.

In 2006, according to prosecutors, Unger told Dr. William O’Donnell that he was giving up his dental practice to do “missionary work” and take care of his ill wife.

“O'Donnell agreed to accept Unger's patients in about May 2006 assuming he’d be paid for his future work,” Assistant U.S. Attorney Ransom Reynolds wrote in a trial brief. But what he didn’t know was that the patients had already prepaid Unger for the future orthodontic care they needed.

Unger allegedly gave O’Donnell a false promissory note of $200,000. “Unaware that the note was fictitious, O'Donnell attempted to deposit the note at his bank and was told it was worthless,” Reynolds said.

Jury selection is scheduled to begin Wednesday in front of Senior U.S. District Judge Thomas McAvoy.

As host of the online radio show “Take No Prisoners,” Unger has been a perennial leader in the sovereign citizens movement. He was one of the more secretive sovereigns in the country – he did not maintain a marketing website and didn’t allow followers to videotape his speaking engagements – but his influence ran deep. He promoted his “Beneficiaries in Commerce” program as a cure-all for everything from tax bills and debt elimination to what he calls “prison extraction.”

Along with James Timothy Turner, who was convicted of tax fraud earlier this year, Unger was one of the original “elders” of the now-defunct Guardians for the free Republics, which in 2010 became the focus of an FBI investigation after the group sent letters to all 50 state governors demanding they leave office. In the scrutiny that followed, Unger began fighting for control of the Guardians, which collapsed amid the tensions, only to regroup months later as the Republic for the united States of America (RuSA).