Max M. Houck, Ph.D., Director at the District of Columbia Department of Forensic Sciences. (Ricky Carioti/The Washington Post)

The embattled director of the District’s first independent DNA lab resigned Thursday, a week after two audits found that the lab’s procedures were inadequate, thereby forcing a national accreditation body to suspend all of the lab’s DNA testing.

Max M. Houck has been the director of the District’s Department of Forensic Sciences since the lab opened its $220 million facility in Southwest Washington three years ago.

In addition to Houck’s resignation, two other senior officials, the chief scientist for the lab and the senior manager for DNA testing, were let go.

The interim director of the lab will be the city’s medical examiner, Roger A. Mitchell Jr.

Last week, the ANSI-ASQ National Accreditation Board determined in its audit that analysts at the lab were “not competent and were using inadequate procedures.” The authors of the audit, which was ordered by the District, gave the lab 30 days to address the concerns.

Despite the sweeping executive personnel changes, people familiar with the operations of the lab said its accreditation still remained at risk as a result of the board’s findings.

The Washington Post first reported last month that District prosecutors within the U.S. attorney’s office alerted city officials to what they described as numerous errors with the DNA analysis performed at the lab. Houck, whose resignation is effective this week, will not be paid for the rest of his contract.

Prosecutors stopped sending DNA evidence to the lab earlier this year.

Houck had a year and a half left in his four-year contract with the city as director of the lab.

Local prosecutors have ordered the review of 182 cases as a result of the errors they said they discovered in the lab’s DNA results. Prosecutors, as well as the accreditation board, had problems with the interpretation in DNA mixtures cases, those in which more than one person’s DNA is present in the evidence.

It remains unclear how many cases have been affected by the lab’s problems. The prosecutors said the errors have not resulted in the dismissal of any cases or in any exonerations.

Prosecutors rely on DNA evidence not just to seek convictions, but also to exonerate.

D.C. Mayor Muriel E. Bowser (D) said earlier this week that she was “very troubled” by the results of the two audits. Bowser spokesman Michael Czin said the mayor was “committed” to working with attorneys, prosecutors, police and other users of the lab “to ensure that everyone can have confidence” in the lab’s work.

In a brief interview Thursday, Houck praised his colleagues at the lab and called them the “finest people” he had ever worked with.

He also said the employees were doing the “best-quality work” they can do with “the resources that they are given.”

He declined to elaborate.

Houck has repeatedly defended the lab’s operations, even after prosecutors said they found numerous flaws in the analyses. Houck argued that his lab technicians followed the same protocol that many city and state labs across the country use in interpreting evidence.

As the city looks for an alternative lab to perform DNA work, city officials said this week that they expect to spend as much as $1 million on using that alternative lab to examine past and current cases.

The audit by the DNA-lab accreditation board criticized the D.C. lab’s practices as not in compliance with FBI standards. It ordered “at a minimum” the revalidation of test procedures, new interpretation guidelines for select DNA cases, additional training and competency testing of the staff.

Board officials said they found that the problems with the lab started in 2013, during its first year of operation.

The audit was published in the same week as a separate review by the U.S. attorney’s office. That review found problems similar to those noted by the accreditation board.

Bill Miller, a spokesman for the U.S. attorney’s office, declined to comment on the personnel changes at the lab. But he said his office was “hopeful” that the lab “will follow the recommendations of two panels of experts so that we have confidence in relying on the lab to perform this important DNA work.”