After repeated challenges to District Judge William Martini’s handling of former U.S. attorney Paul Bergrin’s criminal case, prosecutors are asking an appeals court to remove him, saying his impartiality is in grave doubt.

Martini’s “ability to remain impartial can reasonably be questioned due to a number of statements and actions before, during, and after trial,” Assistant U.S. Attorney Steven Sanders says in a brief to the Third Circuit on Monday.