Dempsey died December 13, 2010, more than three years after being beaten in the face with a landscaping brick. His death was ruled a homicide in January 2011.
Shabazz was arrested in March 2011 on suspicion of second-degree murder while armed.
In charging documents, prosecutors accused him of being the person who wielded the landscaping brick.
He was indicted in Aug. 2011 on a charge of first-degree murder while armed and pleaded innocent at his arraignment soon after.
Today he pleaded guilty to a charge of voluntary manslaughter. He was scheduled to stand trial Monday.
Sentencing is scheduled for Jan. 4.