The two men and two women, all Germans including a married couple, admitted selling copies of 14 works for millions of euros in one of the largest schemes of its kind in recent decades, the court in the western city of Cologne said.
According to the German daily newspaper Bild, the quartet sold a fake Heinrich Campendonk painting to Hollywood comedian Steve Martin for €850,000 ($1.2 million), though the group's biggest sale was another fake Campendonk that went for more than €3 million. Experts said the forged paintings, and their authentication documents, were extremely high quality.
The ring reportedly also swindled German billionaire Reinhold Würth, owner of a museum in Alsace, according to the paper.
Forger Wolfgang Beltracchi, 60, received the heaviest sentence of six years. Beltracchi told a Cologne court he had painted the pictures alone, relying on his cohorts – including his wife – to sell them to art experts, collectors and auction houses. Beltracchi said he learned painting as a teenager, when he helped his father forge fake Rembrandts and Picassos.
His wife Helene, 53, was jailed for four years. Her sister, Jeanette Spurzem, 54, was given a suspended sentence of a year and nine months.
The fourth member of the ring, Otto Schulte-Kellinghaus, 68, was jailed for five years.
The defendants, who could have faced 10 years in prison for organized fraud and forging documents, were offered lighter sentences in exchange for full confessions.