CHICAGO (AP) — Another act in a legal drama featuring a mobster and a violin played out Wednesday when a prison chaplain told a Chicago courtroom minutes before the start of his trial that he was guilty of trying to help an imprisoned mob hit man recover a hidden Stradivarius.

Eugene Klein, a Roman Catholic priest, was accused of plotting with Chicago Outfit enforcer Frank Calabrese Sr. to recover a rare, 250-year-old violin that Calabrese hid years earlier in his Wisconsin home, to kept authorities from selling it. They believed it was worth as much as $26 million.

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Klein, 66, of Mesa, Arizona, wore a clerical collar and gripped a cane as he walked into the hearing, where half a dozen witnesses sat on a back bench ready to testify in the long-planned trial. But the clergyman surprised the courtroom by saying he wanted to forgo the trial and plead guilty.

Several minutes later, he did just that. He answered calmly when U.S. District Judge John Darrah asked him if he did what prosecutors accused him of doing. He leaned forward and responded, “I’m guilty of the offense.”

The offense is the stuff of Hollywood films.

Prosecutors say the plot was hatched in 2011 when Klein was administering communion to Calabrese at a prison in Springfield, Missouri. Calabrese was sentenced to life in 2009 for 13 murders, including strangling some victims with a rope then slashing their throats to ensure they were dead. He was also ordered to pay $4.4 million in restitution. He died in a federal prison in North Carolina in December 2012, aged 75.

After Calabrese’s imprisonment, federal authorities continued to search for his assets. Prosecutors say the longtime Chicago Outfit enforcer wanted to ensure that agents could never get hold of the violin that once belonged to entertainer Liberace, saying he’d rather the priest profited from its sale.

Prison authorities kept Calabrese in strict isolation after he was accused of threatening a prosecutor during his trial in the same Chicago courthouse, allegedly mouthing to the government attorney: “You are a … dead man.”

According to prosecutors, Klein broke prison rules by accepting a note Calabrese passed a note to him — wrapped in religious materials — through the food slot of his cell. It directed Klein to look in a second-floor bedroom, behind a pull-out door and against a wall in the home in Williams Bay, Wisconsin.

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“That is where the violin is,” the note said.

Prosecutors say Klein even called a real estate agent selling the Wisconsin home, posing as a potential buyer. The plan was for another unnamed conspirator to distract the agent during a tour of the home while Klein and another person retrieved the violin.

A federal search in 2010 did turn up a million dollars in cash, diamonds and other valuables in a wall behind a family portrait in Calabrese’s Chicago-area Oak Brook home. But despite searches at the Wisconsin home, no violin was found.

Klein pleaded guilty to conspiring to defraud the United States. Klein, who has been free on bond, will be sentenced June 23; he faces a maximum five years behind bars.

In the Oak Brook search, prosecutors found a certificate indicating the violin may have been a much less valuable one made in 1764 by Giuseppe Artalli, and not by the renowned Antonius Stradivarius.

Asked Wednesday outside the court what motivated him to help the notorious hit man, Klein declined to speak. His attorney, Thomas Durkin, said his client made “an error in judgment,” though he added Klein is partly being made to pay for his good work providing spiritual guidance to convicts, like Calabrese.

“This,” Durkin said about Klein’s prosecution, “ranks right up there with no good deed goes unpunished.”

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