(KRON) -- The Sonoma County Sheriff’s Office is seeking the community’s assistance in locating a missing 87-year-old man considered at risk due to dementia and Parkinson’s disease. Chris Christensen was last seen near Graton around 5 p.m. on Tuesday. Christensen was wearing a navy blue zip-up jacket, jeans and slippers when he walked away from his home in the 5000 block of Vine Hill Road, authorities said. He is described as 5 feet 9 inches tall and having white hair. Missing person Chris Christensen (Photo: Sonoma County Sheriff's Office) “Christensen is believed to be on foot and usually uses a walker, but his walker was found at his house,” the sheriff’s office said. “He does not have a cell phone or any means of communication.” Anyone with information is asked to contact the Sonoma County Sheriff’s Office at 707-565-2121 or call 911 in an emergency. ...read more read less