WHAT STARTED as a six-month experiment in law-enforcement cooperation in the Philadelphia region has become a 30-year-old blueprint on how to catch bad folks across the nation.

Since its inception in 1983, the U.S. Marshals Service Eastern District of Pennsylvania's Violent Crimes Fugitive Task Force has apprehended more than 26,000 fugitives - an average of 867 arrests per year, according to the Marshals Service.

John Patrignani, chief deputy for the U.S. Marshals Eastern District of Pennsylvania, attributes the task force's success to one thing: cooperation.

"The reason it's so successful is because the agencies pool their resources together and the sum of the parts is much more valuable than each individual piece," Patrignani said.

The task force was conceived by the U.S. Marshals as a way to bring together local, state and federal law-enforcement agencies behind a common goal of tracking the deadliest bad folks around.

What was originally a group of fewer than 20 investigators from the U.S. Marshals Service, Philadelphia police and State Police is now a task force of 60 investigators from 11 agencies in the Philadelphia area. It was the first agency of its kind in the country, and now there are more than 80.

Task-force cases are prioritized based on the needs of participating agencies, Patrignani said.

"Even though it's under our umbrella, everybody has an equal voice," he said. "Whatever they bring to us then becomes the task-force priority."

In Philadelphia, that generally means homicide fugitives - more than 1,200 of whom have been apprehended by the force - and those accused of aggravated assault and sexual crimes.

The task force also has another statistic to be proud of: The number of officers it has lost to violence remains at zero, even though they've faced some tense situations.

"It's been a great experience for me personally, and the success we've had was unexpected," Patrignani said. "We were very fortunate that we were in the city that was chosen to start this experiment 30 years ago."

Fugitive hunts have taken the task force far and wide, from Philly's public library to suburban homeless shelters to Cairo, Egypt.

Among the fugitives nabbed by the task force over these three decades:

* Rafael Jones, alleged to have killed Officer Moses Walker in 2012.

* Donnell Murchison, one of the gunmen in the double murder at the Piazza at Schmidts in 2009.

* Darren Bates, a fugitive wanted in Georgia and Massachusetts, caught while updating his MySpace page at the Free Library's main branch in 2006.

* Kyree Slocum, in 2009 in Cairo, wanted in the drug-related slayings of two men in North Philadelphia.

* Edward Gause, a handyman wanted in the beating death of Mayor Nutter's elderly neighbor. Gause was arrested in 2011 in a Delaware County homeless shelter. He was identified by a Daily News reader who saw his photo in the "Week's Most Wanted" feature.