Taleena Kepa-Yim testified that Samita Hall, her mother's boyfriend, wrongly thought her brother was responsible for a small cut on Hall's 1-year-old son. The sixth-grader testified she heard slapping and pounding on the wall and her brother screaming.

Later, she saw through a partially open door Hall beating her brother, she said.

The girl said she saw Hall holding the boy down and "punching him in the face."

"You saw that?" Deputy Prosecutor Glenn Kim asked.

"Yes," Taleena replied.

Taleena, poised and calm during her testimony, was the only witness to say she saw Hall hitting the boy.

Hall, 28, remains in custody in lieu of $100,000 bail. He has a prior assault case involving shaking his 6-week-old son in 1999.

Wearing shorts, a T-shirt, slippers and leg chains, Hall wiped away tears and turned his back to news cameras during the hearing, then broke down in sobs when Tina Marie Kepa, his girlfriend and the mother of the victim, took the stand. Nagata called a brief recess.

The mother testified she lived with her five children — ages 1 to 13 — and Hall at a Herbert Street apartment. The 1-year-old is the only one fathered by Hall, the mother said. The mother said she was at work and Hall was supposed to watch the children the afternoon of Jan. 10.

Taleena testified they were outside hanging clothes when the toddler started crying and went into the apartment after he pulled a basket of toys on himself. Hall later demanded to know who caused a small scratch on his son. Her 4-year-old brother said he did it, the girl said.

"I think he was scared," Taleena testified.

Taleena said she later heard the slapping and then saw Hall hitting the boy.

Victoria Schneider, a pediatrician and child-abuse expert, testified that the boy suffered life-threatening head injuries consistent with being struck multiple times. The boy stopped breathing in the emergency room, but is now doing "very well," Schneider said.

In the 1999 case, Hall was charged with attempting to murder his infant son, but was acquitted of the charge. He later pleaded no contest to second-degree assault and was sentenced to a year in prison.