D.C. Attorney General Karl Racine is calling on Mayor Muriel Bowser to take “immediate action” to change the leadership at the troubled D.C. Department of Forensic Sciences — the city’s crime lab — where issues with handling evidence have lost the lab its accreditation and prompted prosecutors to say they may have to review hundreds of old cases.

“It is now clear that the issues at DFS are deep and broad and require a change in leadership to repair,” wrote Racine to Bowser on Wednesday, referring to director Jenifer Smith and other top leaders at the agency. “I do not believe that DFS can be rehabilitated under its current leadership.”

Racine, whose office — along with the U.S. Attorney for D.C. — relies on the lab’s work in its prosecutions, also disclosed additional concerns about how the lab may have mishandled evidence. While criticism to date has focused on the lab’s handling of ballistics evidence and an effort to conceal the errors, he wrote that over the last two weeks DFS has said it is looking into additional errors by a fingerprint analyst and 10 members of the Crime Scene Sciences Division.

In the case of the fingerprint analyst, Racine wrote that DFS disclosed at least 20 of the analyst’s 147 cases dating back to 2019 are being reviewed.

“These matters are extremely serious,” wrote Racine. “The lab’s actions undermine the integrity of scientific evidence in the District’s most serious criminal cases, faith in the validity of criminal convictions, and public safety in the District of Columbia. We must begin the process of restoring confidence in the District’s crime lab.”

Racine’s letter raises pressure on Bowser and other city officials to make changes at the crime lab, which was created in 2012 but has suffered from persistent problems in handling evidence. In 2015 and 2016 it suspended DNA testing for 10 months over concerns with accuracy.

Smith, who was appointed to lead the crime lab in 2015, did not appear at a D.C. Council hearing on the lab’s errors late last month; Deputy Mayor for Public Safety and Justice Chris Geldart testified in her place. He said there have been some leadership issues at the lab, but would defer to the D.C. Inspector General — which is conducting its own investigation — before issuing any further judgement.

Earlier this week, Ward 6 Councilmember Charles Allen, who chaired the hearing, said he’s lost confidence in Smith’s leadership.

D.C. officials did not immediately respond to a request for comment on Racine’s letter. In an interview, Allen said that Racine’s call for new leadership at DFS is a significant new step in the debate over the crime lab’s future.

“It continues to show that the very people who need to use the independent DFS lab don’t have confidence in it and don’t have confidence in the leadership to get it back on track,” he said. “At the hearing we held… we heard not just from prosecutors, but we heard from the defense [attorneys] across the board. People have lost confidence.”

“It’s clear it’s not just an issue of a misunderstanding or a miscommunication between parties. There is something wrong. There is something wrong in in the ability to to conduct the independent science that is necessary. And there is something wrong with management there,” he added.

D.C. has appealed the crime lab’s loss of its accreditation. In the meantime, a number of forensic tests needed to process evidence in criminal cases is being handled by the Bureau of Alcohol, Tobacco, Firearms and Explosives and private labs.