U.S. District Judge Paul Diamond has referred Philadelphia District Attorney Larry Krasner and Assistant District Attorney Matthew Stiegler to the Department of Justice for investigation into possible obstruction of justice, perjury, and false statements. This referral stems from a contentious review of a 2009 murder conviction, where Diamond disqualified Krasner and Stiegler from participating in the case of Dennis Johnson, who is seeking to overturn his second-degree murder conviction. The judge expressed that he "reluctantly concluded that Philadelphia’s highest law enforcement official and one of his top assistants may have violated the law."

Diamond's decision follows evidentiary hearings that uncovered "troubling" and "disturbing" actions by Krasner and Stiegler, which he believes could be illegal. These actions include allegedly pressuring staff to lie in court, attempting to conceal Stiegler's role in drafting a legal brief, and threatening "consequences" for those who did not follow Krasner’s orders. Testimony from Krasner's own staffers revealed these actions, with the judge finding Stiegler's testimony "often contradictory, evasive, or outright dishonest."

Legal experts have noted that such a judicial referral for investigation is rare but significant, and the U.S. Attorney's Office is expected to take it seriously, potentially leading to a grand jury investigation. This incident adds to Krasner's tumultuous tenure, which has already seen him impeached by the state house and criticized by the Pennsylvania Supreme Court. The investigation's outcome could significantly impact Krasner's political future, as he is currently serving a term that ends in 2030. Krasner has denied wrongdoing and plans to appeal Diamond's ruling.