Cesar Rodriguez clenched his right hand into a loose fist and reached over his left shoulder to demonstrate how he routinely would strike his stepdaughter, Nixzmary Brown, 7, on the upper back to discipline her.

"I probably used all my force," he said yesterday in an interview in jail on Rikers Island. Mr. Rodriguez detailed an approach to discipline that involved hitting the girl, locking her in a room and binding her to a chair all night to keep her from misbehaving. "I told her, 'This is for your own good,' " he recalled.

Nixzmary was found beaten to death in her family's home in Bedford-Stuyvesant, Brooklyn, on Jan. 11. Mr. Rodriguez, 27, and the girl's mother, Nixzaliz Santiago, also 27, are charged with second-degree murder.

In an hourlong interview with three newspaper reporters who were prohibited by jail officials from taking notes, Mr. Rodriguez, in a gray jumpsuit and slumped in a chair, stopped short of admitting that he had beaten his stepdaughter to death, saying, "It's a fragile situation."

But he repeatedly apologized for her death and said he was racked with guilt. He agreed to the interview, he said, to give his side of the story. He said he had been beaten up in jail by other inmates who had heard about the girl's death.

"I'm sorry what happened," he said. "I have a lot of guilt. I have a problem with my emotions. It all built up, and I emotionally just burst."

He calmly and methodically outlined the weeks leading to her death and described his hard-line approach to child rearing that included hitting the children for misdeeds, however minor.

He said that he loved Nixzmary as his own daughter, but she was mischievous, stubborn and disobedient. He tried to run a tight ship at home: For example, the children were forbidden to touch any food in the kitchen without permission. He learned this approach from his mother, who used a belt to strike him and "would beat me till she could not feel her arm anymore."

He listed events that led to a crescendo of a rage at the girl. He said that Nixzmary could not stop breaking her siblings' toys and parents' belongings. She would cut her sister's hair, steal money from her parents, and steal milk from the baby, he said, and she would also "attack" her siblings while they slept.

"This child was a handful," he said.

He said that she recently admitted to burning his 6-month-old son, Gabriel, with a cigarette lighter. Mr. Rodriguez recalled beating her for it and asking her, "How could you do this to a helpless little child?"

He said he would lock Nixzmary in her room at night, where she used a litter box to urinate. Sometimes he would bind her to a chair with twine and duct tape.

Mr. Rodriguez said that often after a beating, he would hold her up to a mirror and urge her that it was easier to just behave.

"I would say: 'Talk to yourself, how do you feel about yourself now? Do you really want to live like this?' " he said. "She would say no."

Nixzmary was losing weight in recent months, he said, because she refused to eat most foods. She weighed 36 pounds when she died.

Mr. Rodriguez said his frustration at her misbehavior continued to grow. Then, in mid-December, he said, his wife had a miscarriage. And three days before Christmas, Mr. Rodriguez said, he was fired from his job as a security guard and could not buy the children presents. Broke, and with bills piling up, he would stay home with the children.

"I just felt like everything was closing in," he said.

As for Nixzmary, the only way to curb her behavior, he said, was to continually follow her around the house.

"I just wanted it all to stop," he said about her misbehavior.

Mr. Rodriguez said that he and his wife asked city social workers for help with Nixzmary's waning appetite and her behavior, but got none. He said he asked his wife to let Nixzmary live with her grandmother in Puerto Rico, explaining that, "It's better for all of us."

A city caseworker advised against this, he claimed.

"She said: 'No, don't do it. You're going to regret it,' " he said.

Mr. Rodriguez added, "If I had to do it all over, I would pressure myself to take her to the precinct and just leave her there."

The last night of Nixzmary's life, there was tension in the home, he said. Groceries were brought home, and Mr. Rodriguez said he began doling out cups of vanilla-strawberry yogurt, but an extra yogurt remained unaccounted for. After an extensive interrogation of the children, he concluded that Nixzmary had eaten it without permission.

He calmed himself by using his computer but found that his printer was jammed. Nixzmary had jammed it with toys, he said.

Mr. Rodriguez refused to say what he did next. He began sobbing and said that he sees Nixzmary in his mind. "I ask her why she had to put me through so much trouble."