WASHINGTON (AP) — The Justice Department engaged in a “disturbing pattern of profound investigative missteps” when it secured an indictment against former FBI Director James Comey, a federal judge ruled Monday in directing prosecutors to produce to defense lawyers all grand jury materials from the case.

Those problems, wrote Magistrate Judge William Fitzpatrick, include “fundamental misstatements of the law” by a prosecutor to a grand jury that indicted Comey in September, the use of potentially privileged communications in the investigation and unexplained irregularities in the transcript of the grand jury proceedings.

“The Court recognizes that the relief sought by the defense is rarely granted,” Fitzpatrick wrote “However, the record points to a disturbing pattern of profound investigative missteps, missteps that led an FBI agent and a prosecutor to potentially undermine the integrity of the grand jury proceeding.”

The 24-page opinion is the most blistering assessment yet by a judge of a criminal case against Comey that is already subject to multiple other challenges, including motions seeking its dismissal on the grounds that the interim U.S. attorney who filed the charges, Lindsey Halligan, was illegally appointed and that the prosecution itself constitutes a vindictive prosecution.

Comey’s lawyers had sought the grand jury materials out of concerns that irregularities in the process may have tainted the case. The sole prosecutor who defense lawyers say presented the case to the grand jury was Halligan, a former White House aide with no prior prosecutorial experience who was appointed to the job just days earlier.