German prosecutors have declined to release jailed art advisor Helge Achenbach on probation, he announced in a social media post on Monday. The district court of the northwestern German town of Kleve will ultimately decide his fate in a parole hearing on Wednesday.

In 2015, the advisor—one of the most prominent figures in the German art world—was sentenced to six years in prison for defrauding wealthy clients out of millions of dollars, including the late heir to the Aldi supermarket fortune, Berthold Albrecht. During trial, Achenbach admitted to altering invoices and adding additional markups to earn himself higher commissions. The court also ordered him to pay back €19.4 million ($22 million) to the Albrecht family. That same year, Achenbach’s advisory business filed for bankruptcy and he was forced to sell off his 1,600-piece art collection to pay back his victims.

In the German legal system, it is unusual for a first-time offender to serve the full duration of his sentence behind bars. Achenbach has been in custody since June 2014 and approaches the four-year mark next month. He is currently participating in a program called “open regime,” which allows low-risk offenders to work outside of prison during daytime hours and return to their cells overnight.

“For first time offenders, the sentence is usually suspended to probation after two thirds,” Achenbach’s lawyer Thomas Elsner told the German press agency DPA. “We see no reason that anything should stand in Mr. Achenbach’s way.” (Elsner did not immediately respond to a request for comment from artnet News.)

The district court of Kleve already agreed to release the advisor last December after he had completed half of his sentence. But the higher regional court rejected his petition for release after prosecutors in Essen filed a complaint to block it. 

“It is not our decision whether Mr. Achenbach will be released on parole or not,” a spokeswoman for the Essen prosecutor’s office told artnet News in an email. “The district court in Kleve will decide on this. We have filed an opinion which hopefully will be considered by the court, but the court is free to decide whatever it finds appropriate.” She declined to disclose the contents of the opinion filed with the court.

For now, at least, Achenbach faces the unusual prospect of having to serve his entire sentence behind bars.