Boy, 6, testifies in death of 4-year-old sister, Marchella Pierce, who weighed 18 pounds when she died

(CBS/AP) NEW YORK - The 6-year-old brother of a 4-year-old New York City girl who weighed less than 18 pounds when she died testifed in the murder case against his mother Thursday.

Tymel Pierce spoke from a closed-circuit TV in another part of the Brooklyn court while jurors watched.

The boy's mother, 30-year-old Carlotta Brett-Pierce, is charged with in the death of her daughter, Marchella Pierce.

The girl's grandmother, Loretta Brett, is also on trial in her death. Both women have pleaded not guilty.

Tymel Pierce said his sister rarely ate or was fed.

According to the New York Post, the 6-year-old said Thursday that he never saw his mother beat his sister.

Marchella was found dead in September 2010. She was tied to her bed, beaten, drugged and starved, prosecutors said.

At the time of her death, prosecutors said her stomach contained one kernel of corn.

Complete coverage of the death of Marchella Pierce on Crimesider