The so-called “Dookhan defense” did not work for one Boston heroin dealer who was convicted by a Suffolk Superior Court jury despite his claim that indicted chemist Annie Dookhan may have tampered with key evidence in the case, prosecutors said.

The defendant, 58-year-old Julio Medina, is one of thousands of convicted and alleged drug offenders who are seeking acquittal or to have their cases dismissed or overturned because of allegations that Dookhan mishandled drug evidence at a state lab where she worked for nine years.

In Suffolk County, more than 200 people have either had cases dismissed or convictions overturned because Dookhan handled evidence used in their trial, said Jake Wark, a spokesman for Suffolk District Attorney Daniel F. Conley.

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On March 27, after deliberating for just 15 minutes, a jury found Medina, whose listed address is the Pine Street Inn homeless shelter, guilty of distributing a Class A substance in a school zone, a statement from Conley said.

Medina, who had 42 previous convictions, was caught selling heroin to an undercover officer in July 2009. The drug evidence in his case was originally handled by Dookhan, prosecutors said.

But that didn’t stop the jury from convicting Medina. Prosecutors said jurors heard, among other evidence, that a second chemist had also examined the powder found on Medina and the substance tested positive for heroin.

Medina’s lawyer, Janet Macnab, who has handled several other cases involving evidence Dookhan may have tampered with, said she will appeal Medina’s case to the Massachusetts Appeals Court. She said the case was “atypical” and did not set “much of a precedent” for others using the Dookhan defense.

Prosecutors will seek to enhance the charges against Medina, based on his record as a habitual offender, at his next trial on April 22, the statement said.