Shane Fox remembers cowering in his bed each night, terrified the monster would appear from the dark once his eyes closed tight.
William Fox, a hero NYPD cop once honored as "Father of the Year," faces 69 years in prison at his Pennsylvania sentencing this week for repeatedly molesting Shane and two other boys.
"He's a true sociopath," said Frank Spinelli, who was abused between 1978-1980 while a member of Fox's Boy Scout troop on Staten Island.
"This is a very sick individual," Spinelli told the Daily News. "The more I learn about him, the more frightening it becomes ."
The sentencing caps a stunning plunge for pervert pop Fox, 66, whose dramatic 1981 rescue of a suicidal teen threatening to leap from a Bowery building briefly made him a national sensation.
The lifelong bachelor even wrote a feel-good book, "The Cop and The Kid."
Thirty years later, prosecutors want Fox declared a violent sexual predator before his Thursday sentencing. He is expected to receive a jail term guaranteeing he dies behind bars.
The ex-cop, arrested in March, cut an August plea deal with prosecutors for sexually abusing his two adopted sons and a third boy over 13 horrifying years.
The last time Fox saw adopted son Shane, the now 32-year-old was testifying about the endless nights of sexual abuse at the hands of his dad.
Prosecutor Anthony Forrey declined to say whether Shane would testify at the sentencing .
But minutes after Shane's chilling recitation of Fox's twisted behavior, the ex-cop ended his trial by entering pleas of no contest to the abuse charges.
The adopted boy was just 14 when he arrived at Fox's home - and was molested in his new dad's bedroom Jacuzzi on their first night together.
The abuse continued for years, usually late at night once the victim fell asleep.
"It happened pretty regularly, like every other night," Shane Fox told the jury. "Depended on the mood he was in, I guess."
Fox recounted how he would try to stay awake all night, hoping to put an end to the relentless attacks by the sexual predator.
"I'd be sleeping and he would come in . . . so I'd move over and he'd start touching me," Shane testified. "I didn't want this kind of action to continue."
Shane, now the father of a 1-year-old girl and stepfather to a 4-year-old boy, came forward in 2008 after catching Fox sexually abusing a 16-year-old adoptee.
Defense attorney Stephen Banik said the guilty plea to incest, involuntary deviate sexual intercourse and other charges was the result of a faulty memory that left William Fox unable to testify.
But Spinelli believes it was hearing the litany of horrors in open court that made something click inside Fox's head.
"He realized, in my mind, that these other people really started to believe all this had happened," said Spinelli.
"He's smart. All of a sudden it was, 'Let's take a plea now.' "