GOLDEN, Colo. (CBS4)– The family of a missing man continues to search for him, more than a month after he went missing.

James Mitchell, 87, was last seen leaving a bowling alley in Westminster Dec. 14, 2017.

READ MORE: 'Little Slice Of Hell' House Under Contract With Cash Offer, Off The Market

James Mitchell (credit: Golden Police Department)

Officers found his pick up crashed into a parked rail car at 10th and Vasquez in Golden. Investigators believe he left his wallet at the bowling alley and went from his home in Arvada to retrieve it.

It’s unclear how he ended up in Golden.

READ MORE: 'Leaving Here Vaccinated': Broomfield County Jail Boasts 85% COVID Vaccination Rate

(credit: Golden Police)

“It was very cold, it was snowing. Mr. Mitchell wasn’t wearing very good clothing to deal with those elements. He was a postal worker so he was used to walking. He could’ve walked further than what we expected. His disappearance is a mystery and we want to try to locate him,” said Golden Police Capt. Joe Harvey.

(credit: Golden Police)

Mitchell’s blood was discovered inside that vehicle.

Mitchell is described as 5-foot-10 and 180 pounds. He has blue eyes and thinning gray hair. He was last seen wearing a blue fleece vest, a solid black short-sleeved shirt, khaki cargo pants, and black athletic shoes with Velcro closures.

MORE NEWS: 'Celebrate Culture, Without Limitations': Denver Juneteenth Kick-Off Concert So Much More Than Just A Show

James Mitchell (credit: Golden Police Department)

The initial search encompassed several miles of paths and trails, rugged hillsides and residential areas and involved personnel from Golden police, three area fire departments, and Alpine Search and Rescue.