UPDATE:The Blanchard Police Department canceled the Silver Alert for 78-year-old Shirley Pickard Tuesday afternoon after she was found. ---ORIGINAL STORY:Police have issued a Silver Alert for a missing 78-year-old woman who was last seen Monday afternoon.Police said Shirley Pickard was last seen around 3:45 p.m. Monday walking on South Harrison Avenue. Pickard has Alzheimer's, so police have asked people who see her to not approach her but to keep an eye on her and contact police.Blanchard police officials also have asked anyone who lives in the 800 block of North Harrison Avenue and has security cameras to check them from around 3:30 p.m. Monday until now. Anyone who has video footage of Pickard walking or has information about her location is asked to call police at 405-485-9391.