Massachusetts is Liberal. The parole board had good intentions, and with Liberals good intentions is all that counts.
They see a man accused of a crime, and they say "What if he is innocent?" They think it is better for a guilty man to go free than for an innocent man to rot in prison.
They see a man convicted of a crime, and they say "He could still be innocent! And, even if he is guilty, perhaps he really has changed. It is terrible to lock up a man who has been reformed."
They never see that their mistakes result in dead poilice officers and families without a husband and father. I guess the Liberals don't care that much for such "little people".