Salvador Dali’s former personal assistant, who was convicted of tampering with the Spanish surrealist’s work and churning out thousands of forgeries, has died, a Spanish government spokesman said. He was 86.

John Peter Moore, a British citizen who was Dali’s closest aid for 20 years, died Monday in Portlligat, just north of the Mediterranean town of Cadaques on the Catalan coast that was so dear to Dali.

Moore and his wife, Catherine Perrot, had run the Perrot-Moore Art Center just steps away from Dali’s main studio home there.

Known as Captain Moore because of his World War II service in Britain’s Royal Navy, Moore accompanied Dali on many of his flamboyant promotional tours around the world.

Later, as Dali became ill and bedridden, Moore’s influence over the artist’s activities increased, eventually ending in scandal.

In October 2004 Moore was accused of dramatically altering Dali’s 1969 painting “The Double Image of Gala,” one of many paintings Dali made of his wife and muse, Gala.

The painting had been stolen from New York’s Knoedler Gallery in 1974, and the FBI and Interpol hunted for it for years without success.

It was found in 1999 in the Perrot-Moore Art Center in 1999. Moore had radically altered the painting, reducing its size and renaming it “Dali Painting Gala.”

A subsequent search of Moore’s home and workshops revealed 10,000 faked Dali lithographs. He was also accused of dealing in stolen art. Moore was detained, but released because of his age.

He was convicted together with his wife of “damaging the moral rights of the author,” but a Spanish court in the northeastern city of Girona did not rule on other accusations because of Moore’s age and the senile dementia he was believed to be suffering.

Moore and his wife were instead ordered to pay compensation estimated at $1.2 million to the Dali-Gala Foundation, charged with looking after the painter’s heritage, as well as paying the restoration costs of the painting.

Dali and Moore first met in Rome, where Moore arranged payment for a portrait of British actor Sir Lawrence Olivier that Dali painted in 1955.

Moore then became Dali’s personal secretary and an expert on the artist’s work. He put together important collections of Dali’s paintings, including “The Apotheosis of the Dollar,” which he sold to the Gala-Dali Foundation.

The extrovert mustached artist died in 1989 of heart failure, leaving an estate estimated at $87.7 million. The exact value is difficult to calculate partly because of the widespread existence of forgeries, many linked to Moore.