The top six men in the crime ring used the hundreds of thousands of dollars they pocketed to live "very high on the hog," she said.
The customers were approached by the scam's salespeople on the street, in bars, and in local beauty parlors; accounts were manipulated through a secret computer installed in a subcontractor's offices in Upper Moreland, she said.
The scamsters accessed the system by using the computer identification of a Comcast employee on disability, one who had been discharged, and others who were taking days off.
The scam came to light after a woman who happened to be a Comcast employee was solicited as she sat in a local beautician's chair, Ferman said.
"She was asked if she'd like to have a discount to her bill in exchange for a payment," Ferman said. "This was reported by the employee to Comcast security."
Comcast's Philadelphia-based public relations team confirmed the existence of the scam Tuesday, saying it had begun its own internal investigation.
"We have been working closely with the Montgomery County D.A.'s Office for several months and want to thank them for their professional and thorough investigation," said spokeswoman Beth Bacha.
Comcast will work to place the customers in authorized service packages over time, but is not expected to press for retroactive payments.
Using the Comcast worker's tip, county detectives began an undercover probe in April 2012. They called the cellphone of a man they knew only as "Nick," identified by Ferman as Nicholas Caputo, 31, of Virginia Beach, Va.
Nick gave them a bank account number; detectives wired $150 and then provided a bank receipt as proof of the deposit, Ferman said.
Nick not only went into the computer system and changed the terms of a special account created by detectives, he also tried to recruit the investigators to become salesmen for the scam, Ferman said.
Nick is still at large, but five others who allegedly developed and ran the scheme are in custody, charged with running a corrupt organization, theft by unlawful taking, computer trespass, and related offenses.
They are identified by police as Alston Buchanan, 28, of the 600 block of Avon Road; Richard Spraggins, 28, Buchanan's roommate; Leighton Harrell, 26, of the 6300 block of North 11th Street; Irving Brandon, 27, of the 6700 block of Sylvester Street; and Kendall Singleton, 26, of the 6600 block of North 18th Street.
Police are looking for 17 other members of the ring, four from Bucks County and 13 from Philadelphia, according to court records.
Ferman said Caputo was the top salesman, and Singleton had access to the subcontractor's computer because he worked at its office in Upper Moreland.
Buchanan is believed to be the ringleader and likely had a separate scam of Comcast accounts operating as early as 2010, Ferman said. Investigators found his checking account going back to December 2010 contained $221,133, mostly in $150 deposits, she said.
Police conducted a search of his home, and seized $100,000 in an attache case and the scheme's records, written in longhand in ringed notebooks, Ferman said.
In an interview with TV reporters Tuesday, Buchanan cast himself as a Robin Hood-type figure, stealing from the Comcast giant to give back to the impoverished customer.
Ferman disagreed: "When you steal from somebody else, you are nothing more than a common thief."
The five are scheduled for a preliminary hearing Sept. 14 in Willow Grove. Ferman said her office would not press charges against the customers who paid for the altered cable service.
"If someone is out there, we would certainly appreciate it if they came forward. That would let us understand the scope" of the crime, Ferman said.
Contact Bonnie L. Cook at 610-313-8232 or email@example.com. Read her "MontCo Memo" blog at Philly.com.