Sean Grayson, the former Illinois sheriff's deputy who was convicted of second-degree murder in the fatal 2024 shooting of Sonya Massey, was on Friday denied early release by a prisoner review board."I am writing to confirm that the Board voted 3-0 to deny Sean Grayson's medical release application," an Illinois Prisoner Review Board spokesperson said in a statement to ABC News. "He will remain in custody."Grayson had asked for an early release because he has cancer. He was sentenced to 20 years in prison in January, after his conviction last October.Popular ReadsThis is a developing story. Please check back for updates.