KANSAS CITY, Mo. -- The family of a 2-year-old boy killed by his mother's boyfriend was outraged when they learned the killer's jail sentence on Wednesday.

Shawrice Winton, 23, was sentenced to 15 years in prison for his role in the death of Keyaun James. The James family was not satisfied with the sentence.

Winton entered into a plea agreement with the Jackson County prosecutor and pleaded guilty to voluntary manslaughter, which carries a maximum 15-year sentence. He admitted in court to striking the toddler in the stomach so hard that he died as a result of the injuries.

The incident happened in February 2008 when Winton and his 17-year-old brother were baby-sitting Keyaun at a house in south Kansas City. He then took Keyaun to a relative's house in Olathe, Kan.

Police responded to a child not breathing at the Olathe residence. The toddler later died at the hospital.

"He should have been charged with first-degree murder," said the boy's great grandmother, Persa Brownlee. "He murdered that baby."

"We asked for 25 years and he should have gotten 25 years,” said Tanna Barnett, the victim's grandmother. ”We told them we weren't satisfied with just 15 years."

The bailiff had to separate the families and escort them to their cars after the sentencing. KCTV5's Heather Staggers said members the James had received threats.