John Barelli worked in the Metropolitan Museum of Art’s security department for thirty-eight years and served as its chief from 2001 until 2016. These days, he drops in every now and then from his home, on the Lower East Side. On one such visit, he cut the figure of a retired financier—striped button-down, navy slacks, loafers. He sat at a table in the Petrie Court café and talked about an incident that he recounts in his 2019 book, “Stealing the Show: A History of Art and Crime in Six Thefts.”

The caper in question was more Monty Python than “Thomas Crown Affair.” And—until now—its outcome has been a mystery. On March 13, 2005, three accomplices entered the museum’s American Wing. Two of them began arguing, distracting the guards, thereby allowing the third, who wore a trenchcoat, a fake beard, and a tweed hat, to covertly affix a painting to the wall using double-sided tape. The art work, a ten-by-thirteen-inch neoclassical portrait in a cheap gilt frame, depicted a woman in a gas mask. The intruder then placed a placard next to the painting; it read “Banksy, 1975. ‘Last breath.’ Oil on board. Donated by the artist.”

That same year, Banksy, the anonymous British street artist, also left works in MOMA, the American Museum of Natural History, and the Brooklyn Museum. At the Met, security staff noticed the contraband painting and removed it within ten minutes—faster than at the other institutions. (A painting of a soup can stayed on the wall at MOMA for three days.) “We took a picture of the scene, made a report out,” Barelli said. “The next day, it hit the papers.”

At the time of the stunt, Elyse Topalian, a Met spokeswoman, said, “I think it’s fair to say that it would take more than a piece of Scotch tape to get a work of art into the Met.”

Barelli often used the incident as a teaching tool when training security personnel. “We not only have to look for things being taken off the wall but things being put on it,” he said. Banksy wasn’t the only artist to hang his own work in the Met. “We usually would give these things away or throw them out,” Barelli said, of the errant pictures.

In his book, Barelli does not reveal what happened to “Last breath.” “Usually something like this is not ‘lost and found,’ ” he said. “If it was lost, it would go to our lost-and-found department.” If it were a pair of sunglasses, say, the museum would wait fifteen days and then give them to Goodwill. “With anything of value—like jewelry, money,” he said, “we would wait thirty days, and, if no one claimed it, it would go back to the person who discovered it. I had a five-hundred-thousand-dollar Cartier bracelet turned in by a waiter at the Met Gala.” Within two days, the bracelet was claimed by its owner, who gave the waiter a reward.

In 2005, Barelli said, most of his staff had never heard of Banksy. Now “Last breath” is likely worth a fortune. In 2021, “Sunflowers from Petrol Station,” a Banksy oil-on-canvas also from 2005, sold at auction for $14.5 million.

“It’s brilliant,” the gallerist Jeffrey Deitch said, after looking at an image of “Last breath.” He included Banksy’s work in “Art in the Streets,” a 2011 show he curated at the Museum of Contemporary Art in Los Angeles. Of “Last breath,” he went on, “It’s a very strong painting, a very meaningful painting. I admire how Banksy can make a profound political statement in this very direct, compact way.”

In the Met café, Barelli said that he knew the painting’s location, but he was cagey. “Well, we didn’t return it to a guard,” he said. “My first inclination was throwing it out, like we do with all this stuff.” Banksy, like the owner of the Cartier bracelet, did try to reclaim his property. “About a month later, I got a call from our legal department, telling me that he wants it back,” Barelli said. “And I said, ‘Well, he can’t have it back. We threw it out.’ ”

But he did not throw it out.

Legally, the picture’s ownership is fuzzy. Raymond Dowd, a Manhattan attorney specializing in art law, said, “A museum director could’ve said, ‘Throw it in the dumpster,’ and some entrepreneurial security guard goes, ‘Well, I got a spot on the wall. I’ll take it out of the dumpster.’ Nothing illegal about that, necessarily. But, when values go up, attitudes change.”

The American Museum of Natural History accessioned its Banksy and put it on display in its Center for Science, Education, and Innovation. A spokesperson for the Met confirmed that “Last breath” is not in the museum’s collection.

In a follow-up phone call, Barelli revealed the full story. “I brought it back to my office, and I talked to my assistant, Ed Devlin,” he said. Devlin, a Second World War veteran, worked for the Met’s security department from 1988 to 2013, after retiring from the N.Y.P.D. He died in 2014. “I said, ‘Ed, get rid of this painting.’ And he said, ‘O.K.’ ” But Devlin didn’t follow orders. “He brought it back and left it in my office,” Barelli said.

Barelli has offered conflicting accounts about what happened to the Banksy next. He’s said that he doesn’t know where it is. He’s also said that, when he retired, “I took it with me.” He added, “If I need some money, maybe I’ll do something with it.” ♦