In closing arguments, French prosecutors urged a 4-year prison sentence and a steep fine be paid by art dealer Guy Wildenstein who is on trial with his nephew Alec, Jr., in a massive tax evasion and money laundering case. He is accused of hiding hundreds of millions of euros in offshore trusts to avoid inheritance taxes, among other alleged frauds.

Prosecutors say Wildenstein should pay a 250-million euro ($276 million) fine, reports Bloomberg. The Art Newspaper earlier reported that the French government estimated the Wildensteins could owe at least €550m, including fines and interest.

Among the revelations in the ongoing case against the art-dealing dynasty, Wildenstein's late father, Daniel, allegedly housed some 2,500 artworks in a Bahamas trust. Guy's lawyers argued the works were not subject to estate tax because they belonged to the trust, and not to Daniel when he died. But prosecutors shot back, “The purpose of the trusts has been perverted and they became piggy banks.”

Testimony in a Paris criminal court continues to Oct. 20.