On September 16, 1963, Officer Sizemore was killed in an automobile accident when his patrol car collided with a fire truck at the intersection of Third Street and Washington Street. Both vehicles were operating their emergency equipment including red lights and siren operating were responding to the same fire when the fire truck struck the police car. Officer Sizemore was taken to the hospital with a broken arm, a broken leg and six broken ribs, internal chest injuries and a skull fracture. He was pronounced dead at 8:18 pm.

He served with the Chillicothe Police Department for 2 years. He was a US Marine veteran and a sergeant in the Marine Corps Reserve. Interred: Boyers Cemetery, Lindley, Missouri.