"It was inevitable her life would end the way it did: battered and beaten, left alone on the floor, moaning until she could no longer hold onto life," Assistant District Attorney Ama Dwimoh told jurors.
Dwimoh told jurors that Cesar Rodriguez, 29, beat his stepdaughter and dunked her in cold water after accusing her of stealing a cup of yogurt.
Before that, Nixzmary was confined to a room with dirty mattresses, a broken radiator, an old wooden school chair with a rope, and the litter box.
The victim was "routinely tied to the chair. She was repeatedly beaten with a belt and fists - his fists," Dwimoh said, pointing to the defendant.
"That little girl had no choice but to defecate in that litter box. ... That was her prison the defendant created for her."
Rodriguez's lawyer, Jeffrey Schwartz, said it was the girl's mother, Nixzaliz Santiago, who killed her. She faces a separate trial later this year.
Schwartz said that his client was an overworked but loving family man, that Santiago was "deeply, deeply disturbed," and that the little girl herself was a troublemaker. He said the girl bullied her siblings, ages 6 months to 9 years, by cutting, hitting and throwing things at them, and even took their food.
The lawyer told the jury that his client responded by tying the girl up, beating her with a belt and - on the night of her death - throwing her in a cold shower, just as his own father had disciplined him.
"But he didn't do it with the intent to hurt Nixzmary Brown," Schwartz said. "He didn't do it to kill Nixzmary Brown."
Investigators say they believe that Rodriguez hit the girl's head on a faucet, causing the fatal injury. Schwartz, however, said that "'Mommy Dearest' took over" and delivered the fatal blow after the shower incident.
Schwartz has sought to blame Santiago for fostering an environment of abuse, and the overburdened city Administration for Children's Services for doing too little to stop it.
During jury selection, Schwartz signaled he also plans to explore the dilemma of how best to discipline children.
Schwartz said outside court Wednesday that his client is guilty only of being "a strict disciplinarian" and reiterated claims that the mother was responsible. Once the jury hears the defense case, he said, "It's going to become very clear who the monster is here."
There had been warning signs for years before Nixzmary died on Jan. 1, 2006, from a blow to the head. School employees had reported that she had been absent for weeks the previous year. Neighbors noticed unexplained injuries and noted she appeared underfed and small for her age. Child welfare workers had been alerted twice but said they found no conclusive evidence of abuse.
The case, coupled with a series of high-profile deaths of children known to child welfare workers, sparked public demands for reform. City officials and lawmakers responded by bolstering the corps of caseworkers and drafting legislation to give life in prison without parole to parents who cause the death of a child under 14 through abuse.
Authorities say evidence against Rodriguez includes photos of the victim and the family's three-bedroom apartment, as well as videotape of the defendant casting blame on the malnourished girl, who weighed 45 pounds at the time of her death. He faces 25 years to life in prison if convicted.
Rodriguez admitted on video that he restrained the girl "by putting duct tape on her hand and tying her to a chair."
On Nixzmary's final night, he said, she enraged him by stealing yogurt and trashing computer equipment.
