Ferber was convicted of being the gunman who invaded a South Philadelphia restaurant in May 1981 and blasted Greek crime-mob boss Chelsais "Steve" Bouras and his friend Jeannette Curro as they dined.
Friel, who died Saturday at age 71, was a lieutenant at the time and head of the Organized Crime Task Force. He found out that the jailhouse snitch who fingered Ferber had failed two lie-detector tests, unknown to then-District Attorney Ed Rendell, in addition to other discrepancies in the original investigation.
As a result, Rendell requested a new trial for Ferber, and he was released after 14 months on death row. Ferber died in December 2008.
Francis P. Friel, who joined the Police Department as a teenager in 1960, died of cancer. He lived in Bensalem.
Friel was credited as the man who ended the murderous regime of the Scarfo mob when the task force he ran arrested Scarfo and 16 associates on racketeering charges. They were convicted and imprisoned.
When he retired in 1989, Friel became director of public safety in Bensalem, and is credited with bringing a new level of professionalism to the department.
"He really stuck his neck out in the Ferber case," writer Allen M. Hornblum said. "He persuaded Rendell to push for a new trial. He sprang an innocent man."
Friel helped Hornblum gather material for his book Confessions of a Second Story Man: Junior Kripplebauer and the K&A Gang.
"He was very sophisticated," Hornblum said. "He knew the King's English and carried himself diplomatically."
Friel was the author with John Guinther of the book Breaking the Mob, about the cracking of the Scarfo case.
In later years, Friel toured the country speaking to various organizations. Once when he went to address the National Organization of Parents of Murdered Children, he was moved by the heartbreak in the audience.
"He was struggling to keep down a bottomless grief, to stare into his own soul," Michael Capuzzo wrote in his book The Murder Room.
Friel, a graduate of St. Joseph's University, is survived by his wife, the former Kathleen Hoover; two daughters, Rosemary Friel and Melissa Hoover; two sons, Timothy Friel and Jeffrey Hoover; a brother, and his former wife, Ida.
Services: Memorial Mass 11 a.m. Monday at St. Ephrem Church, 5400 Hulmeville Road, Bensalem. Friends may call at 10 a.m.