A Clayton man whose mother reported him missing Sunday remains at large despite two possible sightings last weekend in Wake County, authorities said.

Lt. Chris Strickland of the Johnston County Sheriff's Office said witnesses reported spotting John Wrenn Cook, 27, in Raleigh and Cary on Saturday and Sunday, respectively. Strickland said there have been no other reported sightings of Cook, who lives with his mother at 2016 Ridge Road.

The N.C. Center for Missing Persons issued a Silver Alert last Sunday for Cook. His mother told authorities that her son suffers from cognitive impairments and that he had been without needed medications for about a week.

Cook is white, 5 feet 10 inches and 165 pounds. He has brown hair and hazel eyes and a tattoo on one arm of the word “radar”.

He was last seen wearing a green short-sleeve t-shirt, blue jeans and tennis shoes. He drives a light green, 2004 Ford Escort with license plate number MRN-7926.

Anyone with information about John Wrenn Cook should call the Johnston County Sheriff’s Office at 989-5000.