DULUTH — Terry J. Martin took a sledgehammer to the emergency exit and a plexiglass display case at the Judy Garland Museum in August 2005, believing the famed ruby slippers he was stealing were made with real gems.

It wasn't until he met with his jewelry fence that he learned the so-called rubies were made of glass. Knowing that, Martin washed his hands of his renowned prize — one of several pairs worn by Judy Garland in the 1939 classic film "The Wizard of Oz."

"I didn't want anything to do with them," Martin, 76, told Chief Judge Patrick J. Schiltz Friday morning at the federal courthouse in Duluth.

Martin, in a wheelchair and using an oxygen cart, pleaded guilty to the theft of a major artwork and offered a few answers in the decades-old Minnesota mystery that has sparked international interest. The sealed plea, tended to for months by his court-appointed attorney, Dane DeKrey, and Matthew Greenley, special assistant U.S. attorney, includes a recommendation that Martin get credit for time served, according to his attorney.

Martin remained free after Friday's hearing. He left the courthouse with an unidentified woman and man and was driven away in a dark minivan. His sentencing date has not been set but likely will be in a few months.

Martin said that he had cased the museum and didn't notice an alarm on the night he stole the slippers.

"I smacked the glass case, and the slippers were there," he said, his voice raspy.

He told the judge that he doesn't know what happened to the slippers after he met with his fence.

Martin was indicted in May by a federal grand jury. The slippers, on loan from a Hollywood memorabilia collector, were stolen from the museum in the actor's one-time home in Grand Rapids, Minn. They were recovered in a sting operation in Minneapolis in 2018 . No one was publicly linked to the crime for several more years.

Filings in a parallel federal case against Martin implicated him in the thefts of prescription drugs while burglarizing pharmacies in New Hope and Frazee, Minn. It also noted a long criminal history that includes convictions in the 1960s and 1970s for aggravated assault, robbery and burglary.

He also was charged in federal court in the theft of dozens of fur coats from Cedric's in Edina in 1985, but his attorney at the time said Wednesday that Martin was acquitted based on entrapment during a law enforcement sting operation.

The ruby slippers, known as a "traveling pair" that regularly were displayed in public, were lifted from a wooden pedestal in a plexiglass case that could be broken with as little as a fist, museum curator John Kelsch said. He recalled seeing shards strewn about the floor the day after the shoes were taken and the buzz of adrenaline he felt.

During the hearing, Kelsch alternated between taking notes and leaning forward in his front-row seat, seemingly rapt, with his elbows on his knees.

"We do know now, definitely, that Terry Jon Martin did break into our museum, but I'd like to know what happened to [the slippers] after he let them go," Kelsch said afterward.

Martin pleaded not guilty in June and was released with conditions. A jury trial originally was scheduled to start this month. DeKrey described him as currently in hospice care because of chronic obstructive pulmonary disease.

Asked why his client decided to plead guilty now, the attorney was frank. "I think when someone is at the end of their life, they are making decisions that are right for their affairs," DeKrey said. "And, I mean, the short answer is because he's guilty."

Judy Garland was born Frances Ethel Gumm in 1922 in Grand Rapids, where a Judy Garland Festival is held annually over several days in June.

Garland spent her early, pre-California years in the woodsy northern Minnesota city. It's where she first performed a "Jingle Bells" solo, dressed in a handmade white frock, at her father's Grand Theater on S. Pokegama Avenue, according to the museum.

Visitors to the Judy Garland Museum, founded in 1975, remain curious about the story of the stolen slippers, director Janie Heitz said earlier this week.

"It's literally a daily question here," she said.

Star Tribune staff writer Paul Walsh contributed to this story.