Who is Ronnie Joe Waddell from Cruel & Unusual: A Novel and what is their importance?

Ronnie Joe Waddell grew up in a small town and moved to the city as a young adult. In the city, he discovered freedoms he never knew as a child. Waddell went onto become addicted to illegal drugs, including PCP. One afternoon, he was so desperate to find the cash he needed to buy more drugs that he robbed the home of a young television reporter. Unfortunately, the young woman walked in while he was searching her home, and confused by the drugs, he attacked and killed the woman in a brutal fashion.

Waddell is convicted of the crime and sent to death row. Upon his death, Waddell arranged for a friend outside of prison to have the briefcase. His gift, however, caused the death of his friend and helped Scarpetta figure out who changed Waddell's AFIS file and made it appear as though Waddell somehow escaped death row and sent someone else to the chair in his place.