 O'Neill's death was announced in a brief note posted on the Trans-Siberian Orchestra website on April 5, 2017, which cited chronic illness.The Hillsborough, Florida medical examiner’s office determined the official cause of Paul O’Neill’s death as accidental, resulting from an unexpected reaction to prescribed medications to treat his numerous chronic illnesses (including bone augmentation surgery, complications from spinal fusion surgery, heart disease, and hypertension).Found along with O'Neill's body were more than 30 prescription pill bottles in his name.