(CNN) -- Twice each day, 12-year-old Charlie Bothuell V says in court documents, he was forced to do 100 push-ups, 200 sit-ups and 100 jumping jacks. He told child welfare investigators in Michigan that he'd have to curl a 25-pound weight on each arm and do 5,000 revolutions on an exercise machine, and if he didn't finish in less than an hour, he'd have to do the routine again, according a petition filed in Wayne County court in Michigan this week.
The Detroit boy said that he feared being "in trouble again" for not completing his work-out routine. Sometimes he couldn't finish because he was in too much pain, he said.
Charlie made national news in June when his father Charlie Bothuell IV said his son went missing for 11 days, prompting a search that involved the FBI and that ended bizarrely when the child turned up barricaded in the father's basement.
The father was talking live on air with HLN's Nancy Grace when he learned that state police had discovered his son, appearing shocked when Grace told him that she'd just received breaking news about it.
On her show, the elder Bothuell became visibly upset. He started breathing hard and clutching at his chest, and told Grace that he had no idea how his son could have been in the basement.
"I checked my basement. The FBI checked my basement. The police checked my basement," he said on air. "My wife checked my basement. I've been down there several times. We've all been checking."
Bothuell added that his home has been searched repeatedly by law enforcement trying to find his son. Police and the FBI also have said they searched several times and didn't see the boy and now indicate he might have moved during the 11 days -- they won't say yet specifically what their investigation revealed.
At the time, Detroit Police Chief James Craig reacted to the discovery of the boy with his own disbelief.
"I've never seen anything quite like this," Craig told CNN affiliate WXYZ-TV. "We found him barricaded in the basement, behind boxes and a large ... drum. There's no way he could have erected this makeshift area of concealment."
This week, Detroit Police Sgt. Michael Woody reiterated how surprised police were that the boy turned up in the basement. He told CNN, "It's possible" that investigators "didn't see" the boy while they searched the home from attic to basement.
The department is reviewing its procedures, he added.
A petition, signed Monday, and filed in Wayne County juvenile court describes allegations of abuse that the boy says he endured from his father and stepmother, Monique Arnel Dillard-Bothuell.
Neither have been charged; in fact, no one has been charged with anything in the case.
Wayne County child protective services opened an investigation of the family June 23 as FBI agents were looking into the boy's disappearance.
Petitions seeking state custody of Charlie and his younger siblings were filed this week. They say that on June 23, the father "disclosed physically disciplining Charlie V with a PVC pipe. An FBI search of the home produced the PVC pipe with which Charlie V was disciplined. It was disclosed that blood was found on the pipe."
On June 25, the documents say, the boy was found in the basement of the Bothuell home. He was taken to a hospital and a doctor examined him, finding a "half circular scar" on the 12-year-old's chest.
The boy said that scar was a "result of his father driving a PVC pipe into his chest." The child was "also observed to have old scars on his buttocks from being hit with the pipe," the document states.Read more here.