The District’s medical examiner’s office has lost its national accreditation after a professional organization renewed its concerns about its top leader’s credentials.

The National Association of Medical Examiners withdrew the accreditation in March after noting that Chief Medical Examiner Marie-Lydie Y. Pierre-Louis was not board-certified in pathology, as the association requires of top agency officials.

D.C. Council member Phil Mendelson (D-At Large), who oversees the office and other public safety agencies, said he was “concerned” about the loss of accreditation.

“In terms of prestige, it’s a step backwards,” he said.

But Mendelson expressed confidence in Pierre-Louis, crediting her for turning around what had been a trouble-wracked agency in the decades before her 2003 appointment — including the elimination of a once-massive backlog of autopsies.

Pierre-Louis’s board certification is far from a new issue. The D.C. Council voted twice, in 2004 and 2007, to excuse her from a statutory requirement that she be board-certified. The American Board of Pathology does not allow doctors to apply for certification 10 years or more after their most recent medical training.

The Washington Examiner first reported the office’s loss of accreditation Wednesday. Pierre-Louis, 60, could not be reached for comment Wednesday night.

In 2008, NAME issued the District’s office its first accreditation in nearly two decades, but only on a provisional basis, citing Pierre-Louis’s certification status, among other issues.

Mendelson was critical of the association’s decision to withdraw the accreditation based Pierre-Louis’s status, while at the same time acknowledging the agency’s progress.

“They’ve changed the rules on us,” he said.

While the agency’s lack of accreditation could potentially complicate criminal prosecutions, Mendelson said, he was not aware of any case in which it had been an issue.