Updated 11:48 PM ET
CLEVELAND Years before when authorities say Ariel Castro kidnapped two teenage girls and a young woman and held them captive in his basement, he terrorized the mother of his children, viciously beating her and locking her inside the house, her relatives said Thursday.
In interviews with The Associated Press, relatives of Grimilda Figueroa, who left Ariel Castro years ago and died last year after a long illness, described Castro as a "monster" who abused her. Castro once shoved her into a cardboard box and closed the flaps over her head, said Elida Caraballo, her sister.
"He told her, `You stay there until I tell you to get out,"' said Caraballo, who cried as she recounted her late sister's torment. "That's when I got scared and I ran downstairs to get my parents."
Castro, a 52-year-old former school bus driver, was arrested Monday, when one of the three women, Amanda Berry, broke out of his house and called 911 while he was away. Police found the two other women inside. The women had vanished separately between 2002 and 2004 when they 14, 16 and 20 years old.
Castro has been charged with rape and kidnapping. He's being held on $8 million bail under a suicide watch in jail. During his brief arraignment Thursday, he tried to hide his face and didn't speak or enter a plea. A public defender assigned to represent him didn't comment on his guilt or innocence.
, Castro apparently contemplated committing suicide, CBS News senior investigative producer Pat Milton reports.
In a lengthy, handwritten note from 2004 discovered in his house by FBI agents, Castro allegedly confessed to taking the three women and said that he was abused as a child and raped by an uncle, according to a law enforcement source. CBS News correspondent Dean Reynolds also reports Castro called himself a "sexual predator" and provided details about taking each of his victims. He blamed the women for their own kidnappings, but he asks for whatever money he has to be donated to his victims after his death.
Some relatives of Castro have said they were shocked by the allegations against him. An uncle, Julio Castro, said it's been difficult news to absorb.
"Of course we have taken it hard," he said. "We only knew one Ariel, my sweet nephew. He was a sweet, happy person, a musician. We didn't have the slightest idea of the second person in him."
But relatives of Figueroa, Ariel Castro's former common-law wife, said that Castro savagely beat her over the years, shoving her down a flight of stairs, breaking her nose and dislocating her shoulder, among other injuries.
Castro kept Figueroa imprisoned inside her own home, locking the doors from the inside, and forbade her from using the telephone, Caraballo said. After warning her not to leave, he would test her to see if she obeyed, Caraballo said.
"He would go creeping downstairs, not telling her that he's home, spying on her," Caraballo said. "See who she's calling. Next thing you know, he'll pop upstairs."
Monica Stephens, Castro's former daughter-in-law, married Castro's son in 2004 but split from him in 2006. On Thursday, she recalled how her ex-husband told her that he and his mother were beaten by Castro.
"They were like hostages in their own house," she said.
Castro, to frighten his wife, kept a mannequin wearing a dark wig propped up against a wall and sometimes drove around the neighborhood with it, relatives said.
"He threatened me lots of times with it," said Angel Caraballo, Castro's nephew, who used to play with his cousins at the house where the kidnapped women were found. "He would say, `Act up again, you'll be in that back room with the mannequin."'
One day, Figueroa was returning home with her arms full of groceries when Castro jumped into the doorway with the mannequin, frightening her so badly that she fell backward and smashed her head on the pavement, Elida Caraballo said.
In 1996, Castro hit Figueroa for the last time, family members said. After one particularly bad beating, Figueroa ran outside with one of her sons, crying out to neighbors just as the captive women did on Monday, Caraballo said.
"The neighbors went across the street to get her," Caraballo said. "And that was the last time she ever stepped in the house."