A former prison chaplain who pleaded guilty to helping an imprisoned mobster recover a hidden violin avoided any additional time behind bars Thursday when a judge found that prosecutors had not proven that the instrument was a rare 18th-century Stradivarius that purportedly belonged to the late entertainer Liberace.

U.S. District Judge John Darrah sentenced the Rev. Eugene Klein to a single day in prison — time that the Mesa, Arizona, Roman Catholic priest already has served. Prosecutors had sought a five-year sentence.

Klein — who pleaded guilty last year to conspiring to defraud the government — was accused of scheming with the late Frank Calabrese Sr. to find a rare, 250-year-old violin that the Chicago Outfit enforcer hid years earlier in his Wisconsin summer home. In a recent court filing seeking probation, Klein's lawyers argued that the instrument might have been stolen during a 2004 burglary at the home.

Prosecutors say the plot was hatched in 2011 when Klein was administering communion to Calabrese at a prison in Springfield, Missouri, where the mob hit man was serving a life sentence for 13 killings. Prosecutors said Klein broke prison rules by accepting a note from Calabrese wrapped in religious materials and pushed through the food slot of his cell. It directed Klein to look in a pull-out door and against a wall in the home in Williams Bay, Wisconsin.

"That is where the violin is," the note said.

Prosecutors say Calabrese wanted to ensure agents could never get ahold of the violin that once belonged to entertainer Liberace, saying he'd rather the priest profited from its sale. Calabrese died in a federal prison in North Carolina in 2012 at age 75.

A search in 2010 turned up $1 million in cash, diamonds and other valuables in a wall behind a family portrait in Calabrese's Chicago-area Oak Brook home. Despite searches in Wisconsin, no violin was ever found.

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 Italian Antonio Stradivari.

Klein's sentence includes three years of supervised release, with the first six months served in home confinement with electronic monitoring. He also must perform 200 hours community service.