New documents connected to the Massachusetts drug lab scandal show colleagues of the chemist at the center of it had been concerned for years that she was testing too many samples and doing questionable work.
But police reports obtained by The Associated Press show they either convinced themselves their concerns were invalid or told supervisors who didn't intervene to stop her.
The documents also show Annie Dookhan admitted to police in August that she faked test results, forged signatures and skipped proper procedures.
Concerns from her colleagues prompted a supervisor to audit her work in 2010, but there was no retesting of drug samples.
It wasn't until spring 2011, when Dookhan apparently forged a colleague's initials on paperwork after taking 90 samples from evidence, that things started to unravel.
Copyright 2012 by The Associated Press