PHILADELPHIA — Rasheem Hall was handcuffed in a holding cell wedged behind a Philadelphia courtroom, awaiting trial for murder, when he heard someone call from another cell, “Yo! ‘Sheem!” It was Deric “Luke” Williams, a young man Hall knew from childhood, whom prosecutors had brought in from state prison. Williams was there to testify against Hall regarding the murder of Ronald “Hat” Kennel, 54, a bystander in a 2007 North Philadelphia shootout. Williams was the linchpin of the DA’s case: the only person to sign a statement saying he’d seen Hall fire a gun. Now, according to Hall, Williams pro…
