A man already serving a 95-year prison sentence for killing two women in Gary, Ind., was sentenced to serve an additional 20 years in Georgia on Tuesday for the 2003 stabbing death of a Norcross woman.

Anton Kawan Johnson, 33, entered a negotiated guilty plea to voluntary manslaughter for stabbing Aisha Davis, 30. Her body was found in her home at Alexander Apartments on Dec. 5, 2003.

Gwinnett County Superior Court Judge Timothy Hamil sentenced Johnson to the maximum penalty for the charge — 20 years, consecutive to his Indiana sentence — which will ensure he is never released from prison even if he is paroled in Indiana, said Deputy Chief Assistant District Attorney Lisa Jones.

Prosecutors said Johnson was visiting his cousin for a week when he became acquainted with Davis. The cousin lived in the Alexander Apartments and was friends with her.

Davis' sister, Afia Stevens, 40, said she mentioned Johnson only once over the phone. She said Davis told her that Johnson had angrily overreacted when teased about being short.

Authorities still don't know why Johnson killed Davis, but Stevens said "I think he just had a violent, evil nature that just came out and she just happened to be there."

Davis left behind a now 13-year-old daughter, who is being raised by her father, Stevens said.

The crime went unsolved for three years, until former Gwinnett County police detective J.D. Smith submitted blood samples from Davis' apartment to the state crime lab. They matched Johnson's DNA in a federal database.

Johnson was already in prison in Indiana, having been convicted by a jury for murder and voluntary manslaughter for gunning down two women during a drug-related dispute in January 2003. He was not arrested for that crime until February 2004.