(CNN) -- The man police say kidnapped and brutally murdered a 7-year-old Georgia girl pleaded guilty Tuesday and was sentenced to life in prison without the possibility of parole.

Ryan Brunn entered the plea at a hearing in a Cherokee County courthouse, during which he described in detail how he enticed, molested and killed Jorelys Rivera.

The girl's mangled body was found in a trash compactor three days after she went missing on December 2 from an apartment complex in Canton, which is about 40 miles north of Atlanta.

Brunn, 20, who worked as a maintenance man at the same apartment complex, was arrested on December 7 and charged with the crime.

He told the court he had never talked to Jorelys before the day of her murder. He said he devised a plan after he found one of her skates.

Brunn took a picture of the skate and approached her with it, asking if the skate was hers. She said yes, and Brunn promised to take her to it.

Instead, he took her to an empty apartment and instructed Jorelys to pull down her pants. He then put tape over her face and cut her throat with a razor. At this point, she was still alive, he told the court.

So Brunn took Jorelys to the bathroom and beat her to death with the skate. He said he did not have sex with the girl.

Next, Brunn put Jorelys' body in a plastic bag and loaded it into his maintenance golf cart. He put the body in the trash compactor and operated the machine. He then went home and hung out with friends. Later, he again operated the compactor.

Increasingly, Brunn told the court, he grew concerned about what he had done. So he took a receipt, wrote on the back of it, "She is in the trash can," and taped it to the compactor. He admitted lying to investigators who had questioned him about the case. Brunn said he knew right from wrong.

During his testimony, relatives of the slain girl were visibly upset, crying and shaking.

"I would like to apologize for everything I have done," Brunn told her family in court.

Last week, he was indicted on 13 counts including murder, aggravated assault, cruelty to children, aggravated child molestation, enticing a child for indecent purposes, false imprisonment, abandonment of a dead body, making a false statement and sexual exploitation of children.

According to the indictment, Jorelys was severely beaten and stabbed repeatedly in the face, neck and chest.

Brunn's attorney had said previously he planned to plead not guilty. Brunn had no known criminal history, authorities have said.