Friel died Saturday of cancer, according to the Bucks County Courier Times and The Philadelphia Inquirer. The Tomlinson Funeral Home in Bensalem confirmed his death.
Friel graduated from Philadelphia's Frankford High School and began his nearly three-decade-long police career in 1960. He eventually led the Organized Crime Task Force, which worked out of FBI headquarters in Philadelphia and collaborated with state police investigators from Pennsylvania and New Jersey in fighting the city's powerful mob. The task force helped prosecute more than 60 organized crime figures including Scarfo, Harry Riccobene and Salvatore Merlino.
Upper Darby public safety superintendent Michael Chitwood, a Philadelphia homicide detective when Friel was a lieutenant, told The Inquirer that it wouldn't be an exaggeration to say that Friel and the task force brought the local mob to its knees.
"I knew Frank Friel for years," Chitwood said. "He was an intelligent, articulate, hardworking guy."
George Anastasia, who covered organized crime for the newspaper before retiring in 2012, said Friel was the catalyst for a change in the agenda among law enforcement agencies tracking mob crime.
Whereas agencies had previously withheld information from each other as they competed for credit, after Friel became involved, "it was about getting a result and not getting credit," Anastasia told the paper. "It would not have happened without him."
Inquirer reporter Thomas J. Gibbons Jr., a police officer-turned-journalist, recalled Friel as personable and flexible.
"He could interact with all kinds of people, be it law enforcement or the bad guys, and through that, he could bring these cases to a successful conclusion," Gibbons said.
Friel retired in 1989 and was most recently security director for Independence Visitor's Center in Philadelphia.
A decade ago, Gov. Ed Rendell named him head of the state's new gambling commission, but Friel quit a little more than a month later, saying he was tired of media scrutiny.
Friel wrote a book, "Breaking the Mob," which was published by McGraw-Hill in 1990 and republished by Warner Books in 1992.
His wife, Kathleen, called him "a good husband, father and friend," and said the couple enjoyed fishing and boating at their second home in Myrtle Beach, S.C., according to The Inquirer.
Besides his wife of 17 years, Friel is survived by daughters Rosemary Friel and Melissa Hoover; sons Timothy Friel and Jeffrey Hoover; three grandsons; a brother; and his former wife, Ida.