Charles Hill, a widely respected art detective who aided in the recovery of masterpieces by going undercover, has died at 73, according to a representative for England’s Association of Ex-CID Officers of the Metropolitan Police. Arnie Cooke, a close friend of Hill, said that Hill died of a heart attack on February 20.

Hill is most fondly remembered for having helped locate Edvard Munch’s 1893 version of The Scream after it was stolen from the National Museum in Oslo in 1994. That year, with the Winter Olympics set to take place in Lillehammer, Norway, thieves broke into the museum, snapped the wires that held the painting to the wall, and toted it off, leaving behind a note that read, “Thousand thanks for the bad security.”

While working for Scotland Yard’s elite Art Squad, Hill posed as a representative for Los Angeles’s Getty Museum and arranged a meeting with “a dodgy art dealer known to the thieves,” as he told Garage in 2018. After viewing the painting in person and returning to an Oslo hotel, Hill phoned the Norwegian police, who subsequently arrested the dealer. (The dealer was later released without any charges. The painting was recovered in 1996, and it has since returned to the National Museum.)

Hill’s willingness to take major risks in order to find some of the world’s greatest stolen artworks made him one of the most celebrated art detectives in the world. Periodically, he even landed himself in danger. One such occasion came in 1993, after gangsters stole Jan Vermeer’s Lady Writing a Letter With Her Maid from Russborough House in Ireland seven years earlier. Hill went on the hunt, posing once again as an art dealer and claiming this time to be working on behalf of Arab clients. He connected with the Irish gangster Martin Cahill, who brought him to a car park in Antwerp, where Hill personally unwrapped the packaging that held the work. “It’s the greatest masterpiece I’ve had the pleasure to hold,” Hill told Country Life in 2009. The Vermeer, along with a Goya stolen alongside it, were later returned to Russborough House.

[See the top 25 greatest art heists of all time.]

Born in 1947 in Cambridge, England to a British mother and an American father, Hill moved to the U.S. as a child and later fought in the Vietnam War as a paratrooper. Having studied history at George Washington University, he later went to Trinity College in Dublin and then King’s College in London, where he studied theology. “I’d come to the conclusion that I wasn’t going to make it as a clergy man in the Church of England, and I didn’t want to teach because of that wonderful jibe of Henry Kissinger—‘The stakes are so low,’” he told Garage.

He then joined the Metropolitan Police, where he would work for more than two decades. In the process, he would help retrieve works by Titian, Paul Cézanne, J. M. W. Turner, Goya, and many others. In 2002, he struck out on his own and worked freelance. He stopped going undercover, citing the risks of doing so at such an old age.

With his detective work now the stuff of history, Hill has achieved a cult following in recent years. In 2020, the BBC produced a documentary that charted Hill’s efforts to solve the mystery of who stole priceless artworks from the Isabella Stewart Gardner Museum in Boston in 1990. His more than 25 years of research led him to believe the crime boss Whitey Bulger was responsible for the heist. “There is no hard evidence for this but I combat art crime both rationally and irrationally, intellectually and viscerally,” he told the Guardian.

Throughout his career, Hill’s work evinced a curiosity and a genuine passion for art history. “I love art and I know the important thing is to get the stuff back,” he told the BBC in 2019. “Someone has got to do it; who else is going to get these things back if I don’t try?”