German art consultant Helge Achenbach has been arrested after allegations of fraud. The 62-year-old is considered one of Germany’s most influential art consultants, entertaining long-term business relationships with some the country’s wealthiest collectors. According to the state attorney of the city of Essen, Achenbach has been accused of overpricing art and vintage cars he procured for investors. German newspapers Bild and Die Welt have reported that fraud allegations were made by the heirs of Berthold Albrecht, one of the founders of the German discount supermarket chain Aldi, who was one of Achenbach’s most important clients until his death in 2012.