A former chemist at the state crime laboratory in Amherst was sentenced to 2½ years in a county jail Monday for stealing drug evidence for her own gain, said the office of Attorney General Martha Coakley.
Sonja Farak, 35, of Northampton will have to serve 18 months of that prison sentence, followed by five years of probation.
If she is in trouble with the law again or violates probation conditions, she could have to serve the remainder of the sentence.
Farak pleaded guilty in Hampshire Superior Court to four counts of theft of a controlled substance from an authorized dispensary, four counts of tampering with evidence, and two counts of possession of a Class B substance.
“State lab chemists have a duty to uphold the law and protect the integrity of the evidence in their control,” Coakley said in a statement.
“This defendant has admitted to stealing drug evidence from the lab and in some cases even replacing the samples with counterfeit substances in an attempt to cover her tracks.”
As part of her probation, Farak must undergo drug and alcohol evaluation and treatment and complete 500 hours of community service.
The Amherst lab, which stores and analyzes drugs confiscated by local and State Police, first contacted State Police investigators in January 2013 to report a discrepancy in the inventory.
State Police investigators learned that Farak tampered with the evidence, and they learned that she had cocaine in her possession, at her work station, and in her car. She was arrested at her home on Jan. 19, 2013.
A further investigation showed that Frank tampered with four drug samples at the laboratory, and twice mixed drug evidence with fake drugs to hide what she had done. On two occasions, the samples were simply missing.
Farak’s case is not related to that of Annie Dookhan, the disgraced chemist at the center of the Hinton drug laboratory scandal.
Dookhan pleaded guilty in November to widespread tampering with drug evidence, jeopardizing tens of thousands of cases over several years.
She is serving three to five years in state prison.Milton J. Valencia can be reached at mvalencia@
globe.com. Follow him on Twitter @miltonvalencia.