Henry County Sheriff's Office cancels Silver Alert for missing 66-year-old man Copyright 2021 Scripps Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed. Provided The Henry County Sheriff's Department issued a Silver Alert for a man last seen on June 20. and last updated 2021-07-15 22:16:13-04 KANSAS CITY, Mo. â UPDATE, 9:15 p.m. | The Silver Alert for Dennis Ray Knifong has been canceled. EARLIER | The Henry County Sheriff's Department issued a Silver Alert for a man last seen on June 20. Dennis Ray Knifong, 66, was last seen near Missouri Highway 7 in Pleasant Hill. Knifong is roughly 6-feet tall and weighs about 165 pounds. He has white hair and blue eyes and is diagnosed with high blood pressure.