(CNN) -- A former Massachusetts crime lab chemist accused of mishandling evidence affecting hundreds, and perhaps thousands, of criminal cases was sentenced Friday to three to five years in prison after pleading guilty to 27 counts. Annie Dookhan, 36, was arrested last year, accused of cutting corners by visually identifying alleged drug samples instead of performing chemical tests, and then altering the samples to cover up the practice. More than 300 drug convictions involving Dookhan's tests -- conducted from 2003 to 2012 -- have been put on hold since last year in Suffolk County alone, Suffolk County District Attorney spokesman Jake Wark said.
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Annie Dookhan pleads guilty to tampering with evidence, perjury, obstruction of justice
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300 drug convictions have been put on hold in one county alone
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Dookhan cut corners in criminal cases, altered samples to cover up
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Authorities: One person set free because of Dookhan went on to kill someone
Dookhan worked as a state chemist testing drug evidence submitted by law enforcement agencies from 2003 until March 2012, when she resigned, according to the @placeholder attorney general's office.