By Tony Romeo

HARRISBURG, Pa. (CBS) — In a Harrisburg courtroom, a former top Pennsylvania legislative staffer and key witness in the “Bonusgate” scandal (see related stories) was sentenced to prison today.

Despite his extensive cooperation with prosecutors, Mike Manzo — former chief of staff to former Pennsylvania House speaker and former Democratic leader William DeWeese –- was sentenced to 18 to 48 months in prison for his guilty pleas to public corruption charges.

As he left the courtroom, Manzo told reporters he was disappointed by others involved in the case who sought to blame the “culture” of Harrisburg for their actions:

“I never bought into that.  You take responsibility for your own actions.  And I find it offensive how casually some people that were involved in this case were quick to pawn if off on somebody else.”

Meanwhile, while detailing for the judge the extent of Manzo’s cooperation, prosecutor Frank Fina said the former staffer has contributed a “wealth of knowledge” about a “large number of investigations yet to be revealed” that are entirely separate from what the court has seen.

Later, Fina refused to elaborate for reporters.