Surveillance video detailed Gilbertson’s whereabouts on the night of Thursday, December 14 through early Friday morning.
The Minnesota native, living in Denver, was initially out with friends. He continued the night alone and was seen leaving Charlie’s Nightclub on East Colfax just before midnight.
At 12:53 a.m., Gilbertson was captured on video as he left Syntax Physic Opera bar on South Broadway.
Newly discovered surveillance footage put the 29-year-old north of West Alaska Place at 1:05 a.m., between South Cherokee and South Bannock Streets. According to his family, he was seen heading northwest.
Saturday’s search efforts put the group of volunteers and family members at the old Kmart location in Denver, off West Alameda Avenue.
“I'm really hoping that we're going to find him and that he's going to be okay,” Tamra Gilbertson said about her son, “but I also have to be realistic and look at the other side of it also.”
Roughly 130 volunteers split up into five groups.
“I didn't know Adam, but we all feel like we know Adam,” volunteer Hank Provost said.
He’s followed this missing person’s case from the very beginning and said he felt compelled to come out and assist in Saturday’s search.
From 10 a.m. through 4 p.m., volunteers searched the area surrounding Gilbertson’s last known location.
Many volunteers admitted they didn't know Gilbertson either.
“I have my young daughter with me though,” Raven Payment said, “so, I think it's important that we come out as a community to support each other and help out in any way that we can.”
Payment called Gilbertson’s disappearance a parents’ worst nightmare, and offered comfort to Adam’s mother. “As a fellow human being, you know as a fellow woman, as a mother, as someone who loves other people... I think it's important that we're there for her.”
“Somebody knows something, for sure. I know that,” Tamra Gilbertson told Denver7. She pleaded on-camera, “Let us know, so we can get some closure and find some peace in all of this.”
Gilbertson’s Honda Fit was parked down the block from his South Logan Street home, but there was no sight of him. His family told Denver7 his keys were found on a countertop, and Gilbertson’s side-door was unlocked.
His family said they have since moved his belongings back to Minnesota.
He is described as 5-foot-11-inches tall, weighing between 160 to 170 pounds with brown hair and blue eyes.
Gilbertson's family told Denver7 he went to nursing school in Wyoming while he lived in Fort Collins. He graduated from the program last spring and moved to Denver for a nursing job back in August.
If you have information, contact Denver Police at (720) 913-2000, and tell them you're calling about case number 17-837-972.