Rendell said last week the administration was reviewing the board's decision to release Daniel Giddings, who killed Philadelphia Officer Patrick McDonald last week before being killed by police. The review being led by John S. Goldkamp, a nationally recognized expert on incarceration, now includes the fatal shooting of Sgt. Stephen Liczbinski in May.
Rendell said that shooting was committed by an offender on parole for robbery.
"We all understand it was the action of individual criminals that caused these deaths, however I need to know that we are doing everything we can to reduce the possibility of future reoccurrences," Rendell said in a letter to Goldkamp.
A Corrections Department spokeswoman said officials will follow the governor's direction to stop paroling prisoners until the review is complete. A time frame is not known.
"If we're not releasing people on parole, we have to watch out population and deal with it if it continues to grow," said spokeswoman Susan McNaughton.
John McNesby, president of the city's Fraternal Order of Police lodge, advocated similar actions. Of the nine city officers shot over the past year, five were shot by criminals under parole supervision, he said earlier Monday.
"What we didn't sign up for was to be executed," McNesby said. "What we didn't sign up for was to not have the backing of the Philadelphia judicial system - not all, not all, but some of the judges - and the Pennsylvania parole board."
McDonald was shot and killed Tuesday after a traffic stop. Giddings, a passenger in the vehicle, was fatally shot by police responding to McDonald's distress call.
McDonald, whose funeral is Tuesday, was the fifth city officer slain on duty in the last three years.
Giddings had been serving time for a 1998 robbery and aggravated assault, but was paroled and released to a halfway house Aug. 18. He fled a week later and was involved in an assault on police a month before he fatally shot McDonald, authorities said.
A spokesman for Mayor Michael Nutter said the mayor is on-board with the actions taken Monday.
"The mayor is in complete agreement with Commissioner Ramsey, the FOP president and governor in this matter," Nutter spokesman Doug Oliver said. "Clearly, there is a problem with the system here."
A message left for C. Darnell Jones II, president judge of the city's common pleas court, was not immediately returned.
Giddings, 27, served 10 years out of a maximum 12-year sentence. McNesby said he could have been sentenced to up to 45 years for the 1998 robbery, in which he shot his victim in the kneecaps. He had an extensive disciplinary record in prison, spent more than 500 days in solitary confinement, and should not have been eligible for parole, McNesby said.
Associated Press writer Patrick Walters in Philadelphia contributed to this report.
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