The chart above shows the time to complete a criminal drug test. Each dot represents a single analysis, plotted by the date submitted on the X-axis and the number of days to finish testing on the Y-axis. The blue line is a monthly average of testing times. Data analysis and visualization by Chris Amico for WBUR.

In 2009, the U.S. Supreme Court ruled that chemists who perform criminal drug tests must be available to testify to their findings in person, under the Sixth Amendment’s right to confront one’s accusers.

The case, Melendez-Diaz v. Massachusetts, should have made drug analysis take longer — and for most chemists, it did.

An internal report by the Massachusetts Department of Public Health on the now-shuttered Hinton drug lab says Melendez-Diaz “significantly hindered the overall volume of testing at the Lab because chemists spent more time in court.”

Except for Annie Dookhan. From the report:

Despite the significant decrease in overall testing from 2008 to 2009 (a reduction of more than 16,000 samples), Dookhan’s productivity remained relatively stable, decreasing by only 305 tests assigned. In 2008, Dookhan completed 16.3% of all tests in the lab, 22.0% of the total in 2009, 31% of the total in 2010, as well as 24.7% of the total in 2011 despite only testing from January 1 to June 21. These indications should have prompted closer attention to her work.

As her throughput increased, the time it took to complete a drug test fell.

From 2003 to mid-2009, tests gradually took longer and longer to complete, peaking at around seven months, on average, for tests submitted in March 2009. After that, the tests got faster.

Tests submitted in December 2009 took an average of 141 days, or four-and-a-half months. In June 2010, it was 89 days. By December 2010, tests took 65 days.

“You scratch your head and say, ‘How could someone do that?’ ” said Tom Workman, a defense attorney and adjunct professor at the University of Massachusetts School of Law who did his own analysis of the drug lab’s data. “The obvious answer that comes to mind is they weren’t doing the work, they were dry-labbing, simply filling out the paperwork and not doing the work.”

In an interview with Massachusetts State Police, Dookhan admitted to dry-labbing for “two or three years” prior to June 2011, when she was then taken off testing duty.

Dookhan was by far the Hinton lab’s most productive chemist, according to the DPH report:

A review of the volume of sample assignment by chemists shows that between 2004 and 2011, Dookhan was consistently assigned (and presumably tested) more samples at the drug lab than any other chemist, exceeding her peers by as much as 50% more than as the second highest chemist.

In 2010, her throughput was nearly three times that of the next-most-productive chemist: She completed 10,933 tests, while the unnamed other chemist tested 3,839 samples.

Even in 2006, when Dookhan took about three months off work, she outpaced her next-best colleague by 50 percent.

The report shows that the Hinton lab leaned heavily on Dookhan’s productivity. Supervisors lauded her work ethic and assigned her an increasing share of tests.

“From January 1, 2004, through December 31, 2011, Dookhan was assigned 25.3% of all analyses in the Drug Lab and completed 21.8% of all tests conducted by staff,” the report said.

But the report’s authors said this should have been a warning sign: “Dookhan’s consistently high testing volumes should have been a clear indication that a more thorough analysis and review of her work was needed.”

Annie Dookhan far outpaced her colleagues at the Hinton drug lab, according to this chart from an internal DPH report. Investigators compared Dookhan’s testing volume to the next-most-productive chemist for each year, and to the lab overall.