McClaney's sentence is to be served consecutively to his imprisonment in Ohio, where he is scheduled to serve until 2016 for previous convictions of aggravated robbery and voluntary manslaughter, according to the Ohio Department of Rehabilitation and Correction,
McClaney pleaded guilty to the shooting of Rittenhouse in January.
At the time of Rittenhouse's death in 1998, Rittenhouse's mother told police she found her son sitting on a couch with a bullet wound to his head in their East Hamilton Avenue home, according to court documents.
Last year, new DNA evidence and a series of interviews led detectives to McClaney, who is incarcerated in a Toledo prison. McClaney told police he killed Rittenhouse after going to his home to trade for marijuana, documents said.