Police were tipped off that Richardson, who lived in South Philadelphia, was being held against his will in the basement of the house.
Detectives forced their way into the house and found him in the locked basement with "a bed, a chair, a commode," Nodiff said.
"He didn't appear to have any physical injuries, but told detectives that he was very hungry," Nodiff said, adding that police gave him food and drink.
Young "threatened him to sign whatever documents were necessary, including committing fraud and taking his money," Nodiff said.
For months, Richardson's brother, Robert, said, "he was stuck in there with nothing to do."
"He's an evil person," Robert Richardson said of Young.
Detectives are investigating whether Young committed similar fraud involving his common-law wife, who was disabled and died in March of natural causes, Nodiff said. Police said the woman was William Richardson's sister, but Robert Richardson said she was not related to the family.
Police say they do not believe there are any other victims.
William Richardson was kidnapped in April around the 1800 block of Washington Avenue, where he worked as a handyman at a plumbing business.
Young would sometimes give Richardson rides to and from work, his brother said, until one day Richardson didn't come home. His family reported him missing soon afterward.
Since his rescue, Richardson has communicated a strong sense of anger over his captivity, his brother said.
"It's going to take time to get over that," he said.
Richardson will be staying with his brother in North Philadelphia. They met with a reporter Wednesday night at the South Philadelphia home of another brother, James.
Edwina Green, 56, a close family friend, said William Richardson was "so excited" to be free.
Young had a bench warrant for his arrest on a probation violation, according to court records. In January, he was found guilty of endangering the welfare of a child. Other charges, including sexual assault, were dropped. He was sentenced to four years' probation.
He was also sentenced to probation for drug possession in 2004 and burglary in 1980.
Contact Robert Moran at 215-854-5983 or firstname.lastname@example.org, or follow @RobertMoran215 on Twitter.