Glacier National Park officials are seeking the public’s help as they search for a missing man last seen on July 8 on the Highline Trail.

According to a press release issued Wednesday evening, Mark Sinclair, 66, was last seen at approximately 2:30 p.m. on Monday along the Highline Trail headed west at the Rimrocks landmark.

Park staff working in the Logan Pass Visitor Center observed him leaving an unsecured vehicle, keys, and dog in the Logan Pass Parking Lot.

Sinclair was wearing all gray or nondescript clothing (possibly in shorts), a yellow bandanna around his neck, a gray waist fanny backpack, and no hat. His hair is completely white and he may have a beard that is white as well. He is 5 feet, 8 inches tall and weighs approximately 155 pounds.

If you have information about the missing person, please call (406) 888-7077.

Sinclair is a recent resident of Whitefish and worked for a period of time earlier this summer at Glacier National Park.

Search efforts began on Tuesday morning, July 9, and are continuing by ground and air.