Keith Randulich, Ill. Teen, Admits Killing 4-Year-Old Sister

JOLIET, Ill. (CBS/WBBM/AP) A 19-year-old suburban Chicago teen pleaded guilty to first-degree murder Thursday in the killing of his 4-year-old half sister.

Prosecutors say Keith Randulich stabbed Sabrina Clement to death in their Mokena, Ill. home on May 22, 2009.

According to CBS affiliate WBBM, Randulich called 911 about 8 p.m. that day and when police arrived, they found the girl's body in the basement.

The girl suffered what was described in court by Assistant State's Attorney Mike Fitzgerald as "numerous and massive stab wounds to her neck," according to a release from the Will County State Attorney's office.

The teen allegedly told police at the time that he had killed the girl because someone was abusing her. Because he couldn't kill her abuser, Randulich said, he killed his half sister instead.

He took the girl to the basement of his home and stabbed her to death with a steak knife while she was lying on the floor. His parents were not home at the time.

Prosecutors will argue that the crime was brutal and heinous when they ask the judge to hand down a life sentence.

"This was a crime of unspeakable cruelty and horror," said State's Attorney James Glasgow. "One cannot begin to fathom what would prompt a young man to commit such an atrocity against his little sister."

Randulich will be sentenced Jan. 25.