State officials say one person has resigned, another has been fired, and they are seeking disciplinary action against a third person in a shakeup at a state lab in Jamaica Plain in the wake of a controversy over mishandling of drug evidence.

Saying questions should have been raised earlier about the performance of the chemist who is at the center of the scandal, officials said lab director Dr. Linda L. Han had tendered her resignation; director of analytical chemistry Julie Nassif had been fired; and disciplinary proceedings had begun against a third, unnamed person, who was the chemist’s direct supervisor.

Public Safety Secretary Mary Beth Heffernan, Health and Human Services Secretary JudyAnn Bigby, and State Police Colonel Timothy Alben spoke about the situation at a news conference this afternoon in Boston.

Advertisement - Continue Reading Below

Problems with the chemist, Annie Dookhan, were first discovered in June 2011, according to officials.

But the officials said in a statement that the “June 2011 incident was not the first red flag about this chemist’s work performance.”

“The consistent high volume of work she performed throughout her career should have been questioned and reviewed by lab managers,” the statement said.

Bigby said Dookhan’s workload consistently exceeded her peers by 50 percent.

In 2004, for example, Dookhan did 23.6 percent of the tens of thousands of tests done by the lab, officials said.

Dookhan mixed drugs from unrelated criminal cases to assure positive results and manipulated evidence to increase its weight, a prosecutor said Wednesday, The Boston Globe reported today.

State Police have told prosecutors in Eastern Massachusetts that Dookhan handled 60,000 samples from 2003 to 2012, potentially imperiling 34,000 criminal cases, the newspaper reported.