Massachusetts police chiefs, defense lawyers, and prosecutors are preparing for the fallout from evidence mishandling at a busy state drug laboratory, a scandal they say could put felons back on the streets, inundate courts, and damage public confidence in the justice system.  Law enforcement officials are grappling with revelations that Annie Dookhan, for nine years a chemist at a state drug lab, may have contaminated drug evidence, mixed samples from unrelated cases, and manipulated drugs to increase weight, thus stiffening defendants' penalties.  Dookhan is believed to have handled about 60,000 samples, potentially affecting 34,000 criminal cases.  Legal specialists warn there may be more fallout to come: Immigrants convicted of drug charges may have already been deported. Property seized in drug cases may have already been sold off. And even jury selection in future drug trials could be affected.  "There are so many different avenues of collateral consequences," said David J. Breen, a Boston University School of Law professor and former prosecutor in New York and Massachusetts.
The Boston Globe