A federal judge has ordered that Bulgarian national Dimitar Dimitrov, 58, an alleged ringleader, who was arrested last month in the Unites States, remain behind bars.

In overturning a magistrate's order, US District Judge Kent Dawson described Dimitar Dimitrov as a "lifelong criminal who has little regard for others" and said his character is "one of dishonesty and violence," Las Vegas Review-Journal reported.

Dimitrov and 10 other people were indicted in May on a variety of federal charges related to the theft of cars from auto dealers and cash from bank ATMs.

In all, the ring defrauded a dozen valley auto dealers out of USD 1.6 M worth of cars and stole at least USD 700,000 from ATMs over the past two years, prosecutors allege.

At a detention hearing for Dimitrov on May 24, Assistant U.S. Attorney Kathleen Bliss told U.S. Magistrate Robert Johnston that Dimitrov had a criminal record in both the United States and in Bulgaria, where he is alleged to have maintained ties to organized crime figures.

Bliss said Dimitrov was overheard on court-approved wiretaps allegedly threatening to "barbecue" a witness against him by tying the witness to a tree and pouring gasoline over him.

Johnston, however, ordered Dimitrov released on USD 100,000 bail with house arrest and electronic monitoring.

Bliss later appealed to Dawson, citing in court papers another threat against a former crime associate who owed him USD 59,000. Wiretaps, she said, show Dimitrov allegedly vowed to get crime figures in Bulgaria to "cut off the ears" of the former associate and "use them as cigarette holders."

Dimitrov's lawyer, Todd Leventhal, contends in court papers that Dimitrov is not as bad as prosecutors claim.

He said his client fled Bulgaria in 1990 for political reasons and originally settled in New York, where he worked as a cab driver. An auto accident left him permanently disabled, and now he may have prostate cancer.

But Leventhal was unable to garner any sympathy from Dawson.

The judge, who said he was familiar with the wiretaps because he had approved most of them, wrote in his opinion that Dimitrov's threats included "mayhem, mutilation and torture."

Dawson said he was convinced that Dimitrov was a danger to the community and a flight risk.

"No condition or combination of conditions of pretrial supervision will be sufficient to protect against those risks," Dawson wrote.

Prosecutors, meanwhile, are fighting to keep one of Dimitrov's reputed top associates, Dragomir Taskov, behind bars.

Bliss argued in court papers Monday that Taskov, a Canadian citizen who spearheaded Dimitrov's auto theft operations here, is a flight risk.

Authorities found several false identification cards for Taskov when they searched his Las Vegas home in 2008, and he has shown other members of the crime group how to enter and leave the United States through Mexico, Bliss alleged in the court papers.

She alleged that Taskov also showed a friend how to smuggle people into the United States through Canada.