Early on the morning of 11 April 1934 the sacristan of St Bavo’s Cathedral in Ghent stumbled on a crime scene. The Ghent Altarpiece – a vast polyptych, painted by Hubert and Jan van Eyck – was in its usual place in the Vijd chapel; but where one of the panels depicting the Just Judges had been, there was now a gaping hole.

By then the Ghent Altarpiece already had a chequered history. Commissioned by the wealthy merchant Jodocus Vijd in the early 1420s, it had been installed in the family’s chapel in the hope of encouraging worshippers to pray for his soul. But it was also intended as a testament to his wealth and prestige. One of the first artworks ever to be painted in oils, it was undeniably lavish, overflowing with saintly figures and glittering colours. In the centuries that followed it became one of the most desirable artworks in Northern Europe. It was nearly destroyed by Protestant iconoclasts; plundered by Napoleon and taken to Paris; broken up, pawned and sold to the king of Prussia; and finally captured by the German army during the First World War. 

But the theft came as a profound shock, all the same. Belgium was then in a febrile state. Two months earlier King Albert I had died in a mysterious accident; and just weeks later two of the country’s leading banks had unexpectedly collapsed, ruining businesses and wiping out savings. The loss of such a prominent artwork shook the Belgians’ already wounded pride more than public opinion could bear. It was vital to catch the thief – and quickly.

Hope and despair

There was just one problem: the authorities were baffled. When the chief of police, Antoine Luysterborgh, visited the scene later that morning nothing made any sense. How had the thief broken into the cathedral, disassembled the altarpiece and escaped with a panel that was almost 1.5m tall, all without anyone noticing?

Tips soon came flooding in. The police were inundated with reports of suspicious-looking people who had been seen lurking. But nothing came of any of them and two months passed without any serious leads. Then, on 1 May 1934, the bishop of Ghent, Honoré Coppieters, received a ransom letter. Signing himself ‘D.U.A.’, the writer demanded one million francs for the panel’s return and invited the bishop to reply by placing a classified advert in the newspaper La dernière heure. There was no question of paying such a sum, of course; but the polite tone of the letter led the police to believe that the panel might soon be within their grasp.

A delicate negotiation now began. And it soon bore fruit. In a third letter, dated 28 May, the thief revealed that he had left the outer part of the panel – a grisaille portrait of St John the Baptist – in the left luggage office at Brussels North station as a goodwill gesture. Frustratingly, no one who worked there could remember anything about the man who had deposited it, other than that he was middle-aged; but an air of quiet optimism now took hold.

Ten more letters were sent, each as earnest and reasonable as the next. Then they suddenly stopped. The case, which had seemed so promising over the summer, ran cold. With no other hard evidence to go on, the police despaired of ever catching the thief, let alone finding the missing panel.

Exit Goedertier

Another unexpected twist was around the corner, though. On 25 November 1934 a stockbroker named Arsène Goedertier had a stroke at a meeting in Dendermonde, just outside Ghent. Realising that death was near, Goedertier asked for his lawyer, Georges de Vos. In a hoarse whisper he revealed that he was the thief. The proof, he claimed, was in his desk. De Vos didn’t need telling twice. Rushing round to Goedertier’s house, he found copies of the letters, a notebook covered in diagrams and the draft of a final, unsent message. He also discovered the receipt for the left luggage office at Ghent station, where the typewriter used to produce the letters was later found, and a set of keys, including one which was identified as belonging to the rood loft in the cathedral.

There was no doubt that Goedertier was the thief. But why had he done it? The obvious explanation was money. Six years earlier, Goedertier had founded an investment company with some friends from church. This set up and ran plantations in the Belgian Congo, capitalising on the huge incentives being offered to private businesses by the government. After the Wall Street Crash, however, it ran into difficulties and, six days before Goedertier’s death, it had been declared bankrupt. It was not inconceivable that the theft was connected. Had Goedertier stolen the panel to cover the company’s debts?

It hardly seemed likely. Despite the bankruptcy Goedertier was not short of cash. After the First World War he had opened a brokerage house with his wife and it had made him a millionaire. His home was luxuriously decorated, he employed a large staff of servants and drove a magnificent car. He was also extremely pious. He was even one of the founders of a Catholic co-operative. It was unlikely that he would have stooped so low as to blackmail his own bishop for something as crude as money, especially when he had more than enough already.

But if Goedertier didn’t do it for the cash, then why did he? Was it just the thrill of the crime? Goedertier was an avid fan of true crime. He owned a large collection of detective novels and loved following police investigations in the news. What was more, he also had a taste for art. He was an accomplished painter. He had studied at the Royal Academy of Art in Dendermonde and had a particular talent for portraits. After a lifetime of respectability, did he simply long for a bit of excitement?

The hunt

More pressingly, what had Goedertier done with the panel? On his deathbed he told De Vos that it was somewhere no one could touch it without arousing public attention. But where? There was no sign of it in his house, nor in his safety deposit box at the Crédit Anversois. It had to be elsewhere.

The search proved disastrous. The police made only the most cursory enquiries. Although De Vos was quick to report Goedertier’s confession, he was not properly interviewed until much later. To make matters worse, the public prosecutor decided to keep Goedertier’s involvement under wraps. Not until six months later was the press informed and a reward offered for any information. This, admittedly, turned up a few small details. But by then memories had already begun to fade and the case once again fizzled out.

There the mystery lay – until, that is, the Second World War. After the invasion of Poland, the Nazi government began looting occupied territories for their artworks. It was feared that if – or rather, when – Germany attacked Belgium and France, a similar fate would await the Ghent Altarpiece. In early May 1940 the Belgian government therefore decided to send it to the Vatican for safekeeping. While it was en route, however, Italy declared war on France. It was then redirected to Pau, in the Pyrenees, where it was placed under the protection of the Vichy government. The Nazis were not to be denied, however. In 1942 they seized the painting and shipped it off to Schloss Neuschwanstein in Bavaria, where it remained until heavy bombing forced them to move it to the Altaussee salt mines for the rest of the war.

The missing panel irked them, though. At about the same time as the altarpiece was taken to Germany, Joseph Goebbels sent Oberleutnant Heinrich Köhn to Ghent to track it down. A cunning, relentless man, Köhn was a born detective. After interviewing De Vos, Goedertier’s widow and anyone else who had known the disgraced stockbroker, he concluded that the panel must have been hidden somewhere in the cathedral itself. He was so confident, in fact, that on 20 May 1942 he informed the bishop of his intention to search the building. Yet Köhn never found anything.

Guilty bishops?

What went wrong? According to Karel Morties – a former chief of police who has spent longer investigating the case than almost anyone else – Köhn was right about the panel’s location, but made a fatal mistake in revealing his plans to the bishop. As soon as the bishop heard about the search, he allegedly sent word to Canon Gabriel Van Den Gheyn, the custodian of the cathedral treasures. Unbeknown to Köhn, Van Den Gheyn had learned about the theft, and the location of the panel, from Goedertier in confession years before. Before the Germans could find it, therefore, he spirited it out of the cathedral in the dead of night and concealed it in a nearby home.

But this hardly seems credible. If Van Den Gheyn had indeed heard about the panel in confession he could not have told anyone – including the bishop – without violating canon law. This leaves us with an impossible situation. If he did not tell the bishop anything, how did the bishop know to warn him about the search? But if he did share Goedertier’s secret, why did the two men not move the panel earlier?

More likely, Goedertier left the panel in the care of an accomplice. In his letters, he had mentioned unnamed ‘friends’, and it would have been virtually impossible for him to have removed the panel on his own. Perhaps one of them kept the panel? During the original investigation police had looked at two figures, Achiel De Swaef and Oscar Lievens, without finding any proof. It is not impossible that there were others.

Ninety years after the theft, Ghent police continues to keep the case open. And there is still some hope. In 2014 the historian Paul De Ridder even claimed to have traced the missing panel to the house of a well-known local family. For now, however, the mystery remains as perplexing – and as tantalising – as ever. 

Alexander Lee is a fellow in the Centre for the Study of the Renaissance at the University of Warwick. His latest book, Machiavelli: His Life and Times, is now available in paperback.