A US man has pleaded guilty to a museum heist in which he stole a pair of ruby red slippers worn by Judy Garland’s character Dorothy in The Wizard of Oz.

Terry Jon Martin believed the rubies were real gems until a jewellery fence – someone who buys stolen goods – told him they were made of glass.

His attorney told the Associated Press his client, 76, was now in poor health and “facing his own mortality”.

The shoes are among only four authentic pairs that remain from the 1939 film.

Lead character Dorothy would click their heels three times and repeat “there’s no place like home” to return from the Land of Oz to her native Kansas.

With their ruby sequins and glass-bead bows, the stolen pair was one of several used by Garland while filming the musical.

In 2005, the slippers were on loan to the Judy Garland Museum, in the late actress’ hometown of Grand Rapids, Minnesota, from Hollywood memorabilia collector Michael Shaw.

Martin, from the nearby city of Duluth, took a sledgehammer to the museum’s emergency exit and lifted the item – which was insured at $1m (£824,000) – from its plexiglass-encased display pedestal, believing the rubies were real gems.

But when a stolen goods buyer informed him the rubies were not real, he “didn’t want anything to do with them”, Martin told a federal judge on Friday.

He was not publicly linked to the crime until 13 years later, when an FBI art crime team recovered the slippers in a sting operation after a man approached the insurer and said he could help get them back.

Federal prosecutors announced Martin’s indictment in May, adding that the current market value of the slippers stood at about $3.5m.

Local media footage showed the thief entering the federal courthouse in Duluth on Friday in a wheelchair, donning a paper mask and carrying an oxygen tank.

Ahead of the hearing, his attorney, Dane DeKrey, told the AP that Martin was in poor health and had been cooperative with him.

“I think Terry is facing his own mortality, and I think when people are reaching that point in their life, they cut through the pleasantries and talk turkey,” he said.

Martin – who has a previous conviction, in 1988, for receiving stolen goods – remains free until he is sentenced, although no date has yet been set.

Federal sentencing guidelines recommend eight to 10 years behind bars, his lawyer has said.