Willy Vandersteen's family set out to clear his name, but they ended up doing just the opposite.
Wim at the Forbidden Planet blog has the story: Vandersteen was a popular Belgian cartoonist who created the popular comic Suske en Wiske (also known as Bob et Bobette), which ran in the Belgian Journal de Tintin and its Dutch equivalent, Kuifje. Born in Antwerp in 1913, he took up cartooning around 1939 and got his first newspaper strip, in the paper De Dag, 1941. His career gathered momentum during the war, and Suske en Wiske was first published in 1945. His work continued to be popular until his death in 1990.
Although Vandersteen was a well loved cartoonist, rumors have long circulated that during the German occupation of Belgium, he did illustrations for books and magazines that were sympathetic to the occupation and had overtones of anti-Semitism. The drawings, which were signed with an alias, were done in a style similar to Vandersteen's, but throughout his life, the artist denied any connection with it. Finally, to put the rumors at rest, Vandersteen's family and his publisher, Standaard Uitgeverij, hired a group of independent historians to research the question.
What they found was the opposite of what they expected: After looking at records unearthed in post-war collaboration trials, the historians determined that Vandersteen did indeed do the drawings. His family was dismayed. This early work seems to be out of characters; In both his life and his subsequent work, Vandersteen promoted tolerance and justice, and during the war, perhaps at the same time he was working for collaborationist publications, he drew anti-German, pro-Resistance cartoons.
There's a book in the works, naturally, that may shed some light on Vandersteen's dual personality, although it's entirely possible that in very difficult times, he took the gig for the money and didn't feel good about it. It's not unusual for freelancers to compartmentalize their work, serving two clients at once with differing points of view. But given this particular client, it's not surprising that Vandersteen tried to take the secret to his grave.
(See the Willy Vandersteen article at Lambiek.net for more about the cartoonist.)