One of his daughters, Angie Gregg, told CNN that she "just wanted to die" upon hearing her father had been implicated.
But looking back, she thinks there were signs of something awry -- such as how her father "kept his house locked down so tight" and would sometimes leave mysteriously for an hour or so, then return, with "no explanation."
"Everything's making sense now," Gregg said. "It's all adding up, and I'm just disgusted."
Source: Death threat if newborn died
According to the initial incident report, the women said Castro first chained them in the basement but later let them live upstairs on the second floor.
The women went outside only twice during their ordeal -- and just "briefly" at that, Cleveland Public Safety Director Martin Flask said.
Most of the time the three would be in different rooms, though they interacted occasionally and came to "rely on each other for survival," said a law enforcement source with direct knowledge of the investigation.
One thing they could count on was that their alleged captor wouldn't let them out.
Castro would often test his captives by pretending to leave, the law enforcement source said. Then he'd suddenly return; if there were indications any of the women had moved, they'd be disciplined.
While Knight told investigators Castro forced her to miscarry her own unborn children, she said he ordered her to deliver Berry's child, according to a police source familiar with the investigation.
The baby was delivered in a plastic tub or pool in order to contain the afterbirth and amniotic fluid, the source said.
Panic ensued soon after. The child stopped breathing, and everyone started screaming, the source said, citing accounts by the young women.
Knight said Castro threatened to kill her if the baby did not survive, the initial police report states.
"What's most incredible here is that this girl who knows nothing about childbirth was able to deliver a baby that is now a healthy 6-year-old," the source said.
'I don't think she would have lived very much longer'
Knight remained hospitalized in good condition Thursday, said MetroHealth Medical Center spokeswoman Tina Shaerban-Arundel.
The others held -- Berry, her 6-year-old daughter and Georgina "Gina" DeJesus -- are back with relatives.
FBI specialists who talked with them feel they "desperately need space and time," said McGinty.
"These victims need to be decompressed," he said. "They need a chance to heal before we seek further in-depth evidence from them."
Those close to them, as well as residents of Cleveland and beyond, are trying to make sense of the alleged depravity.