AMHERST, Massachusetts (WHDH) -- A Massachusetts state crime lab chemist is now at the center of another drug testing controversy.
Sonja Farak, 35, was arrested and charged with tampering with drug evidence and two counts of possession of drugs.
"After testing drugs, determining them to be the actual drugs, cocaine and heroin, the allegation is that this chemist then removed that substance the real substance, substituted a counterfeit substance in order to cover the tracks of what she had done already," said Attorney General Martha Coakley.
Police said the discovery was made by supervisors at the Amherst state crime lab where Farak works. The lab is currently handling 750 cases, but in light of the investigation it will temporarily close. For now, prosecutors say there's no reason to believe any results have been compromised.
"In other words, these drugs were tested, they were tested fairly. The certificates were not impeached in any way, but we allege for personal use that the drugs were then taken and in her possession," said Coakley.