A worker at the Deutsches Museum in Munich stole paintings from the collection, replaced them with rough forgeries, then sold the originals at auction, according to the judgment of a court in the city this month. The thief used the proceeds to finance a luxurious lifestyle, the judge said.

The worker, who is identified in court documents by the initials S.K., in keeping with German privacy law, was convicted of stealing four paintings by early-20th-century German artists from storerooms over nearly two years and avoiding detection by replacing the artworks with copies. He then sold three of the pieces at auction; the fourth failed to find a buyer.

Judge Erlacher of the district court in Munich sentenced the man to a commuted prison term of one year and nine months and ordered him to repay the roughly $63,000 he got from the sale. The thief’s evident remorse and willingness to work with the court were given as a reason for the lenient sentence.

He was 23 or 24 years old when he was hired as a technical employee of the museum, in May 2016, according to court documents. He left the museum’s employ in 2018.

“The accused shamelessly exploited the access to the storage rooms in his employer’s buildings and sold valuable cultural assets in order to secure an exclusive standard of living for himself and to show off with it,” according to the written judgment.

The Deutsches Museum specializes in scientific and technical displays and does not exhibit art. However, that does not stop private collectors and foundations from bequeathing their art collections to it, Sabine Pelgjer, a museum spokeswoman, explained. The museum’s assets include hundreds of pieces of often valuable art that remain in storage.

The museum noticed something was wrong when an in-house appraiser went to check one of the paintings, “The Frog Prince Fairy Tale” by Franz von Stuck, for an unrelated reason and noticed that the canvas on his workbench was not a precise match with its catalog entry.

“In the end it was pretty easy to recognize as a forgery,” Pelgjer said.

The museum then went through its art inventory and found three other counterfeit pieces.

The thief sold the von Stuck piece through a Munich auction house, giving it a new name and claiming that he had inherited it from his great-grandparents.

The painting sold for €70,000 to a buyer from Switzerland.

Two other paintings, by Eduard von Grützner and Franz von Defregger, sold for considerably less: €7,000 and €4,490.50.

The fourth painting — “Dirndl,” also by von Defregger — did not sell, which prompted the man to take it to a second auction house and eventually lower the initial bidding price to €3,000, but it still did not attract a buyer.

It remains unclear whether the thief made the forgeries himself.

The case has echoes of another scandal that transfixed the museum world this summer. At the British Museum in London, a tip-off that a curator was selling stolen collection items on eBay snowballed into a crisis for the institution and led to its director’s stepping down.

During the brief trial in Munich on Sept. 11, the thief told the judge that he was surprised how easy it had been to steal the paintings.

Noting that the man had to submit to a criminal record check when he was hired, Pelgjer, the museum spokeswoman, said, “We actually do have pretty secure facilities, but when it is one of your own employees, it’s pretty hard to keep safe.”