GHENT, Belgium — The main suspect in the legendary art heist is said to have whispered with his dying breath: “Only I know where the ‘Adoration’ is…”

More than seven decades later, the whereabouts of a panel belonging to one of Western art’s defining works, the “Adoration of the Mystic Lamb,” also known as the “Ghent Altarpiece,” remains a mystery.

If the stunning heist of Picasso, Monet and Matisse paintings in Rotterdam, Netherlands, last month focused attention on the murky world of art theft, the gothic Saint Bavo cathedral in Ghent has been at the center of a crime that has bedeviled the art world for decades.

“The Just Judges” panel of the Van Eyck brothers’ multi-panel Gothic masterpiece hasn’t been seen since 1934, when chief suspect Arsene Goedertier suffered a stroke at a political rally and died after murmuring those fateful words to a confidant.

The theft has kept the country enthralled ever since, with its heady mix of priceless art and scintillating detective story.

Ghent was hit by two thefts on the night of April 10, 1934: “One was a wheel of cheese,” said detective Jan De Kesel. “The other was the panel.”

That slowed up the investigation of the art theft, in which a minor panel of the “Adoration of the Mystic Lamb” representing St. John the Baptist, was also lifted.

“Don’t laugh,” said De Kesel, one of a long line of detectives searching for the lost work: “It was 1934, there was an economic depression — and the wheel of cheese had priority.”

The probe went nowhere until the St. John the Baptist panel was found that year in the luggage claim of a Brussels train station wrapped in brown paper. It wasn’t the sign of a guilty criminal conscience — just an extortion ploy proving that the thief, or thieves, had “The Just Judges.” A note demanded a million Belgian francs, a massive sum at the time, for the panel’s return.

The local bishop produced only a fraction of the ransom demand and more extortion letters followed.

Then Goedertier died, yielding another clue in his apparent confession: “In my office … drawer … closet.” There, copies of the old extortion letters and the draft of a new one were found.

Adding to the theft’s mystique, this last one read: “’The Just Judges’ are in a place where neither I nor anyone else can take it without drawing the public’s attention.” Police also found indecipherable drawings possibly pointing to a hiding place.

Ever since, Belgium has been in the grip of a decades-long treasure hunt, one that has drawn detectives of every ilk: cab drivers, computer scientists, lawyers and retired police inspectors, among others.

From divining rods to endoscopes to SS Nazi search parties, it has all been to no avail. Overanxious amateur sleuths have even drilled holes into important monuments on the hunch the panel might be there.

One of the more popular theories is that Goedertier, a stockbroker, may never have taken the panel out of the cathedral, but hidden it somewhere inside. But lifting every pane or tile in the massive St. Bavo would carry a prohibitive cost and risk damaging the historic edifice.

“There are not even indications as to what part of the church it might be in,” said De Kesel. “And I tell you, there are an awful lot of nooks and crannies.”

Perhaps closest to the mystery these days is art restorer Bart Devolder, at Ghent’s Museum of Fine Arts. He is working on the most ambitious restoration yet of the 15th-century painting. Devolder hopes the five-year restoration will raise interest in the theft of “The Just Judges,” which was replaced in 1941 by a much-lauded copy from art restorer Jozef Vander Veken.

The ongoing restoration “offers the opportunity for a new boost to look for it,” Devolder said in an interview while taking a break from work. “It really bothers me that the work is not complete.”

“The Adoration of the Mystic Lamb” was finished in 1432 as medieval times gave way to the Renaissance, and the work’s stunning detail and sense of light were at the time unsurpassed.

Much as the restoration of Rome’s Sistine Chapel a dozen years ago wiped the grime off Michelangelo’s multicolored glories, there is hope the same will happen to the “Ghent Altarpiece” under Devolder’s efforts.

“If we remove the yellowing varnish, people will see the genius of Van Eyck even more,” Devolder said.

He maintains hope that he will one day get his hands on “The Just Judges” — for restoration only of course. “I am sure it will take a great deal of work,” he said, “depending where it was kept.”

He made an appeal to whoever might have possession of the panel.

“We have an extra easel here,” said Devolder. “They can quietly bring it in here. No questions asked.”