FAIRFAX COUNTY, Va. (DC News Now) -- It's been more than two weeks since the truck of a missing 80-year-old man was discovered in Arlington. However, Fairfax County police said the man's whereabouts remain unknown. Robert Howard Williams, 80, who disappeared from Fairfax County, has been missing since before Thanksgiving. PREVIOUS COVERAGE | VSP, Fairfax County police searching for missing 80-year-old man last seen in Falls Church area During the investigation, police discovered Williams was last seen just days before the holiday on Nov. 25, in the 2100 block of Westmoreland St. This is in the Falls Church area. On Saturday, Nov. 30, VSP issued a critically missing adult alert for Williams, and investigators believed that he was driving a 2008 Silver Toyota Tacoma. As the search for Williams continued, authorities found the suspected pickup truck in the 5700 block of Fairfax Drive on Dec. 1. This is just over three miles from where he was last seen. DC takes ‘giant’ step forward to control RFK Stadium site Since then, Fairfax County police told DC News Now that no new details or updates have become available in the case. Williams is around 5 feet and 11 inches tall. He has gray hair with brown eyes and weighs around 180 lbs. According to VSP, Williams' disappearance poses a credible threat to his health and safety. Anyone with information about his disappearance is encouraged to call the Fairfax County Police Department’s dispatch at 703-691-2131 or 911.