The District’s crime lab erroneously concluded bullet casings found at the scenes of two fatal shootings were fired from the same gun, then sought to minimize the mistake, according to a panel of independent forensic experts commissioned by the D.C. attorney general.

The experts have recommended that the lab stop all firearms analysis in the wake of its handling of evidence in the 2015 shootings. A detective testified about the flawed analysis before a grand jury, and the two men charged in both cases now argue the case was tainted.

Federal prosecutors said in court filings the error was uncovered when outside examiners took a fresh look at the evidence. The auditors concluded the D.C. Department of Forensic Sciences (DFS) failed to own up to the mistake even though internally it reached the same result after a follow-up examination. The auditors also said management pressured an analyst into changing their second finding. They said the lab “misrepresented” the mistakes to two national forensic accrediting boards.

“In the opinion of the audit team, such actions by management indicate a lack of adherence to core principles of integrity, ethics, and professional responsibilities,” the report says. Even though the incident is largely confined to the firearms unit, the report adds, “management has cast doubt on the reliability of the work product of the entire DFS laboratory,” which includes numerous units other than firearms examiners.

The 20-page report, which was filed in D.C. Superior Court, calls on the lab to “immediately cease performing casework” and bring in outside experts “to determine if additional errors have been made.” It also says the competence of analysts should be evaluated and they should be retrained.

DFS, an independent city agency, operates out of a $220 million facility in Southwest Washington that opened in 2012. In addition to firearms analysis, the lab handles the examination of DNA and other evidence collected in criminal investigations.

In filing the report, federal prosecutors said the District’s Office of the Inspector General in December opened a criminal investigation into the lab and has conducted interviews and reviewed thousands of documents. The status of that investigation is not clear and a spokesperson at the inspector general’s office declined to comment.

It also is not clear what — if any — impact the report will have on the lab’s operations or any court cases in which analysts there played a role. Prosecutors had routinely relied on the lab’s analysts to testify about their findings at trials.

Jenifer Smith, director of the Department of Forensic Sciences, would not discuss the audit’s conclusions. In an emailed statement, she said such a review must be conducted by a national accrediting body and the document filed in court “does not meet this criteria and cannot be considered an audit of the department.”

The U.S. attorney’s office for the District declined to comment on the audit or say whether it has or will stop using the department’s work in criminal cases. The office of D.C. Mayor Muriel E. Bowser (D) did not respond to a request for comment.

The audit followed prior concerns by prosecutors about DFS. In early 2020, the U.S. attorney’s office, along with the FBI, investigated the lab’s operations and raised questions about the “integrity and competence” of employees. A report by prosecutors said they found lapses in ballistic examinations, including some that lacked supporting documentation.

Then in November, prosecutors brought the newest problem with the lab’s firearms evidence finding to the 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 handle the investigation. The three have worked closely with federal prosecutors and have testified as experts on behalf of the government on past cases.

Earlier this month, they filed their report in the case of Rondell McLeoud, 27, who, along with Joseph Brown, 31, are charged in two 2015 fatal shootings.

The first homicide happened a little past noon on Aug. 18, 2015, as Amari Jenkins was standing in the 4900 block of East Capitol Street SE. Authorities said a minivan pulled up and two assailants jumped out with semiautomatic handguns. Both opened fire, killing Jenkins and littering the pavement with 15 casings from a 10 mm firearm, authorities said.

Three months later, on Nov. 12, Antwan Baker was shot shortly before 11 a.m. in the 5300 block of Clay Terrace NE, and a second victim was wounded, authorities said. As in the earlier killing, authorities said, the attackers left numerous spent shells on the ground, including a dozen casings from a 10 mm weapon.

The wounded man, who fired back with a gun of his own, identified Brown and McLeoud as the assailants, authorities said. They said other physical evidence and witness statements also linked the two men to the Aug. 18 slaying. At the scene of the second killing, 10 mm shells were also recovered. Investigators sought to link those shells to the 10 mm shells in the earlier homicide.

“Analysis by a firearms examiner from the Department of Forensic Sciences determined that a 10 mm cartridge casings [sic] recovered from the shooting” of Baker “matched a 10 mm cartridge casings [sic] recovered from the shooting” of Jenkins, a prosecutor said in an early court filing.

When prosecutors brought their evidence before a grand jury, a D.C. homicide detective testified about the lab’s finding of a match, according to court papers. The jurors then voted to indict the two men in both cases.

As the case was moving to trial, the homicide prosecutors then hired the outside analysts to retest the cartridge shell casings. But instead of bolstering the case, they determined the casings were not fired from the same gun.

Prosecutors then informed the city’s lab of the contradictory finding.

According to the audit, two examiners took another look at the bullet casings and decided the outside experts were correct.

But the lab did not report that its initial analysis was wrong, according to the audit. Instead, the audit said, lab employees at a meeting determined their report should say their finding was “inconclusive.” The auditors said lab employees “misled their accrediting organization, oversight boards, clients, and other stakeholders about their processes and conclusions.”

Prosecutors have pressed forward with the cases against McLeoud and Brown, saying in court papers that ample evidence ties them to the shootings.

Attorneys for the men say their clients were harmed by the false grand jury testimony and have asked for the charges to be dismissed. That request remains pending before Judge Milton Lee.

“I’m representing a man charged with first-degree murder. The entire rest of his life depends on the outcome of this case,” said McLeoud’s attorney Steve Kiersh. “And here you have the Department of Forensic Sciences violating all rules of protocol, methodically and credibility. This had the potential for a horrible result based on this transgression by DFS. Fortunately, it was uncovered.”

The firearms examination unit is not the only part of the lab that has come under scrutiny. In 2016, after prosecutors said there were errors in cases analyzed by the DNA lab, the lab suspended DNA forensic work for 10 months as new practices were adopted.

Marrisa Geller, spokeswoman for the Office of the Attorney General, which handles prosecutions of juvenile defendants, said the office has ceased using the firearms lab for its criminal cases.

“We hope the questions we still have about the Department of Forensic Sciences are resolved so that we can go back to working with the Firearms Examination Unit on criminal cases,” Geller said in a statement.

Attorneys at the District’s Public Defender Service said they have asked federal prosecutors to “conduct a comprehensive review of post-conviction cases” handled by the lab. Jessica Willis, special counsel for forensic science for the service, said the U.S. attorney’s office has not responded to their request. “PDS has been attempting to assess the impact the lab’s problems have had on former clients’ cases,” she said.

Other local attorneys are pressing for prosecutors to reexamine all gun cases handled by the city’s forensic lab.

“Retesting all the firearms evidence in past and present cases is a herculean endeavor, but must be done in the interest of justice,” said defense attorney Corinne Schultz.

Paul Duggan contributed to this report.