Finding and stopping city government corruption is the mission of a new task force headed by a just-hired veteran prosecutor, Philadelphia District Attorney Seth Williams announced yesterday.

Patrick Blessington, a former city prosecutor for 11 years who spent the past 14 years in the Pennsylvania Attorney General's Office, is now the D.A. Office's chief of special investigations, with oversight of the Corruption Prosecution Task Force.

"Pat will be responsible for long-term investigations and prosecutions often involving police misconduct, government and city corruption and grand-jury investigations, similar to the priest-abuse case," Williams said at a news conference.

The task force will help the D.A.'s Office work in a more collaborative fashion with city police and state and federal prosecutors in the fight against corruption, Williams said.

"I really look forward to serving the district attorney and the citizens of this city again," said Blessington, 52, who worked as a city prosecutor from 1986 to 1997. He will report directly to Deputy of Investigations Curtis Douglas.

While Blessington is charged with rooting out corruption across city government, Williams mentioned the Police Department as an area that needs attention.

He said that although the total number of police corruption cases involves a small percentage of the police force, such cases erode public confidence. Under former D.A. Lynne Abraham, many people believed that such cases took too long to investigate, Williams said.

* In other news, Williams also addressed the controversy brewing involving the imminent departure of his office's second-in-command, First Assistant D.A. Joseph E. McGettigan, which the Daily News reported yesterday.

Although sources inside the D.A.'s Office said that McGettigan was leaving over conflicts concerning Williams' questionable hiring and promotions practices and the management of the office, Williams said that the departure was due to a medical leave for surgery, which starts Monday.

Williams said that he was not sure if McGettigan, 62, would return to the office, though sources confirmed that he will not. He was not among the phalanx of officials flanking Williams during the news conference.

Williams conceded that some of his decisions have drawn in-house criticism.

"Every decision I've made here, there are probably a handful of people that disagree," he said. "I live with a wife, a mother, three daughters. I don't think anybody agrees with me in my home.

"I come to work, it's probably two people who agree with me. So, I recognize that. There have been a lot of challenges. I didn't think that everything would be smooth sailing becoming district attorney."