The District’s crime lab must halt examinations of evidence collected during criminal investigations after its accreditation was suspended by a national board, according to the District.

An official with the office of Mayor Muriel E. Bowser (D) said that the suspension is in place for 30 days and that the city will appeal the finding.

The move Friday comes after an independent panel of forensic experts concluded the lab made an error testing ballistics evidence in two 2015 murder cases and then refused to acknowledge the mistake. The auditors also determined the lab then “misrepresented” the mistakes when the accreditation board investigated the allegations.

The ANSI National Accreditation Board alerted the D.C. Department of Forensic Sciences (DFS) on Friday that it had suspended its accreditation for all forensic evidence investigations, including DNA analysis, firearms and rape kits.

It is unclear what prompted the board to suspend the lab’s accreditation. Calls and emails to the board were not returned late Friday or Saturday.

DFS, an independent city agency, operates out of a $220 million facility in Southwest Washington that opened in 2012 and was hailed as the city’s first independent lab, not associated with the city’s prosecutors.

The suspension means the District’s police department, federal and local prosecutors, and the city’s medical examiner will have to contract with outside labs to process evidence.

Chris Geldart, the deputy mayor for public safety and justice, said the national board was also considering pulling the lab’s accreditation as part of a “possible accreditation withdrawal.”

“We are implementing actions to ensure continuity of services through outside contract support while we will work with our judicial partners to assess and address the concerns and to ensure a fully accredited forensic crime lab that is independent of MPD and federal prosecutors,” Geldart said in a statement. He said the suspension was 30 days and the city would appeal.

On Friday night, the lab’s director, Jenifer Smith, sent an email to her employees alerting them of the suspension.

“The laboratory will be appealing this determination. I will keep you all informed as the situation progresses,” Smith wrote, according to a copy of the email obtained by The Post. “I am proud of the work that all of you do everyday, especially during these unprecedented times. WE ARE....DFS!”

Calls and emails to the lab’s spokesman, Darrell Pressley, were not returned Saturday. A spokeswoman for the U.S. attorney’s office declined to comment. A D.C. police spokesman referred calls to lab officials.

D.C. Council member Charles Allen (D-Ward 6), who chairs the public safety committee, said on Twitter that the suspension was “deeply concerning” and he planned to call a public hearing.

In a statement, the D.C. Office of the Attorney General, which handles cases of juveniles accused of crimes, said it “hopes to again be able to call DFS forensic expert witnesses in criminal and juvenile cases once these troubling problems are addressed.”

Disputes between federal prosecutors within the U.S. attorney’s office for the District and the lab’s technicians have been ongoing since 2015. In 2016, after prosecutors determined there were errors in cases analyzed by the lab’s DNA unit, the lab suspended DNA forensic work for 10 months as new practices were adopted. The head of the lab at the time, Max M. Houck, resigned.

In early 2020, the U.S. attorney’s office, along with the FBI, investigated the lab’s firearms unit and raised questions about the “integrity and competence” of employees. No criminal charges were filed against anyone within the lab, but prosecutors issues a report in which they said their investigation found lapses in ballistic examinations, including some that lacked supporting documentation.

The recent questions about the lab’s firearm unit have led many defense attorneys to ask prosecutors for a review of criminal cases reviewed by the unit.

The pulled accreditation comes as the city is experiencing an increase in violent crime.

Corinne Schultz, a defense attorney who works in the District, said she worries that hundreds of criminal cases delayed due to the pandemic could be further delayed as authorities identify outside labs to review evidence.

Jessica Willis, special counsel for the District’s Public Defender Service, said she also expects additional delays in cases.

“Our clients have sat in jail during an unprecedented pandemic waiting for their day in court. Despite this news, trials must go forward,” Willis said.

In November, prosecutors brought the newest problem with the lab’s firearms evidence finding to the D.C. inspector general’s attention.

The office, after conducting its own interviews with lab employees, sought forensic specialists to investigate the lab’s practices. The Office of the Attorney General and the U.S. attorney’s office identified three independent experts — Bruce Budowle, James Carroll and Todd J. Weller — to conduct an audit. The three have worked closely with federal prosecutors and have testified as experts on behalf of the government on past cases.

In the 2015 cases, DFS examiners erroneously concluded that bullet casings found at the scenes of two fatal shootings were fired by the same gun, according to documents filed in D.C. Superior Court. Outside experts who reviewed the evidence before trial came back with the opposite conclusion — ruling out a match.

The audit found that the lab did not own up to the mistake even when its analysts, after a fresh look, agreed with the new findings.

Defense attorneys for two men charged in the killings have asked a D.C. Superior Court judge to dismiss the cases. The attorneys argued the grand jurors voted to indict their clients after hearing about the erroneous ballistics analysis.

Peter Hermann contributed to this report.