Sean Grayson cause of death update: How did ex-deputy convicted in Sonya Massey killing die?

Former Illinois sheriff’s deputy Sean Grayson has died in prison while serving a 20-year sentence for the 2024 killing of Sonya Massey. Grayson’s attorney announced his death Sunday, August 23, but no cause of death has been released so far. Grayson had stage 4 colon cancer and had recently sought medical release from prison because of his condition.Sean Grayson died in prison while serving 20 years for Sonya Massey’s killing. Here's what we know about his cause of death. (Sangamon County Sheriff’s Office)The Illinois Prisoner Review Board rejected that request in July. Grayson was convicted of second-degree murder in October 2025 and sentenced to 20 years in prison in January 2026. He was 32.What was Sean Grayson’s cause of death?There is no confirmed cause of death for Sean Grayson at this time. His attorney announced that he died in prison, but did not immediately provide further details about what happened.Grayson had been battling advanced colon cancer. According to Capitol News Illinois, he was diagnosed in 2023, and the cancer later spread to his liver and lungs. His health became a major part of his legal case this year as he asked to leave prison on medical grounds.His request was denied by the Illinois Prisoner Review Board in July. The three-member board voted unanimously against his medical release, meaning Grayson remained in custody until his death.