BOSTON (AP) — The interim head of the state's public health department plans to step down next month.

Dr. Lauren Smith took over the agency last fall after the resignation of John Auerbach. He stepped down amid an investigation into management lapses at a former state drug testing lab. A former chemist at the lab, Annie Dookhan, has been accused of mishandling drug samples or faking test results.

Shortly after beginning her tenure, Smith was thrown into the forefront of the state's response to a deadly national fungal meningitis that was linked to a Framingham compounding pharmacy.

Smith plans to step down on May 10 after finalizing regulations for medical marijuana in Massachusetts.

Secretary of Health and Human Services John Polanowicz thanked Smith for her "strong leadership and vision" and said a search for a successor has begun.