Last month, Ross Ulbricht was found guilty of seven charges related to his role in operating the quasi-anonymous online market Silk Road. Now Ulbricht's lawyer, Joshua Dratel, is fighting for a retrial.

In a court filing submitted on Friday, Dratel argued the prosecutors in the Silk Road trial failed to disclose evidence in a timely manner. The appeal stated that the "suppression of particular evidence" had a significant impact on the outcome of the trial. Dratel also notes that an expert witness, Andreas M. Antonopoulos, was on a plane at the time the submission of his proposed testimony was due. USA Today reports Antonopoulos would have challenged the prosecution's analysis of evidence "that linked Silk Road-generated bitcoins to an electronic wallet held by Ulbricht."

This appeal is not a complete surprise. Dratel also called for a mistrial several times during the case, and was denied by the judge each time.

The court has until April to respond to Dratel's filing. Ulbricht's sentencing is scheduled for May 15th.