BOULDER COUNTY, Colo. The Colorado State Patrol is investigating a hit-and-run collision on Highway 36 in Boulder County that left a 75-year-old man dead at the scene Sunday night.Around 11 p.m., troopers said the victim was walking down the middle of the highway near Longhorn Road when the driver of a northbound pickup struck and killed the man, whose identity has yet to be released.The white pickup truck took off after the crash.The suspect vehicle is believed to be either a 2007-2012 GMC Sierra or a 2007-2012 Chevrolet Silverado with a chrome front bumper, black grill, and possibly black wheels.The pickup truck may have damage to the front driver-side bumper, as well as damage to the grill and fog light housing.If you witnessed the crash, have any information, or have not spoken to investigators, please contact Colorado State Patrol Dispatch at 303-239-4501. You can reference case number 1D244004.