(CLEVELAND) -- Cleveland cops were summoned six times to handle accusations that accused kidnapper Ariel Castro had assaulted or menaced people, including three alleged beatings of his wife, but he was only convicted once and was never sentenced to any prison time.
One of the accusations against Castro was that he battered his wife while she was recovering from brain surgery, according to newly released police records.
It is unclear whether any of the reported incidents could have led police to the three women allegedly held as sex slaves for a decade in his house, but the number of times his name pops up in the Cleveland police database is far more than the two incidents police originally reported.
There was no immediate response Monday from police or prosecutors.
Castro is currently being held in isolation and on suicide watch in a Cuyahoga County prison. According to prison documents obtained by ABC News, guards are instructed to check on him every 10 minutes, looking for any signs that he could potentially hurt himself, including inspecting cups for chipped edges.
Castro mostly sleeps, according to the prison logs obtained by ABC News, but guards have found him wandering his cell naked and using a string pulled from a rug to floss his teeth.
Castro's ex-wife, Grimilda Figueroa, who died last year, accused Castro of assault in 1989, 1993 and again in 2005, three years after he allegedly abducted his first victim Michelle Knight in 2002.
Castro was "a monster," according to Figueroa's family members who spoke to ABC News last week on the condition of anonymity. He was "nice when he was outside but behind closed doors he was an animal. Two faced. He had done terrible things to her [Figueroa] and treated her like trash."
Castro's own brothers, Pedro and Onil Castro, called him a "monster" in an interview with CNN.
Castro's alleged kidnap victims -- Michelle Knight, Gina DeJesus, Amanda Berry and Berry's 6-year-old daughter -- were freed last Monday. Castro has been charged with rape and kidnap, but prosecutors said they will bring additional charges that could potentially carry the death penalty.
At the time of Castro's arrest, police said they had only twice been called to his home, but newly released records indicate they had significantly more contact with Castro.
Castro was first accused of abusing Figueroa in 1989.
He "slapped the victim several times in the face... He slammed her several times against the wall and several times against the washing machine," according to a police report from the time.
Published reports citing court records say that Castro pleaded no contest and was given probation.
In 1993, police were called to the Seymour Avenue address where Castro would later allegedly keep his kidnapping victims. Figueroa told cops that Castro "threw her to the ground, hitting her about the head and face and kicking her body."
The woman had recently had brain surgery and still had wounds from the operation, according to police documents obtained by ABC News.
Their son Anthony, who was 12 at the time, ran out of the house to get help when he saw his mother being abused.
Castro was arrested, but it appears Figueroa dropped the charges against him.
Police last dealt with Castro in 2005, one year after he allegedly kidnapped DeJesus, then a 14-year-old student who was friends with his daughter. DeJesus was the last woman Castro is accused of kidnapping.
Castro got into a fight with Figueroa about testifying against her then boyfriend Fernando Colon. Colon was accused in 2004 of raping the two young daughters of Figueroa and Castro.
Castro threatened to beat Figueroa if she failed to testify, according to the police reports. Figueroa later dropped her complaint against Castro, records show.
Colon was later convicted of child abuse and served three years in jail.
Following the incident with Castro, Figueroa filed for a restraining order against him.
Other incidents included a complaint that Castro threatened to run over a man while dropping his children off at a bus stop in 1996.
Castro, who was a Cleveland bus driver until he was fired, was also investigated in 2004 for inadvertently leaving a student on his bus. A neighbor who accused Castro of stealing a chain-link fence told police that Castro threatened him. A second neighbor made a similar complaint to police in 1996, telling cops that Castro threatened, "I'm going to get you, b*tch!" as he drove past.
It is unclear from police records what action, if any, was taken.
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