Relatives of 37-year-old Cameron Collin have headed stateside in an attempt to locate the Airdrie man who was last seen Thursday at a party outside Billings, Montana.

Collin attended a bachelor party for one of his friends Thursday and was not heard from in the days that followed. His loved ones held out hope that he would make an appearance at the wedding on Sunday but he never showed.

“I’m overwhelmed,” said Julia Collin, Cam’s sister. “My dad decided to drive down to Montana so I told him to come pick me up.”

"For him to disappear for this many days is definitely out of character."

Cam Collin had been partying with friends on a rural property roughly 25 kilometres southeast of Billing on Thursday.

“I know he was drinking,” said Julia. “They put him on a couch to go to sleep, or sleep if it off a little bit, and the next thing they knew he was gone.”

Considered a social butterfly, Collin’s friend hoped he had simply met someone at the party but there were several details that gave them cause for concern. His jacket and belongings were still at the party and the last phone call he made was to the hotel where he had reserved a room. He had called to ask the hotel to hold his reservation as he’d be late to arrive but he never checked in.

When Collin failed to show up at the wedding on Sunday his friends notified police. “They said that he was the kind of person that would be capabale and might even try to make a cross-country trek so we covered that by helicopter,” explained Sheriff Mike Linder of the Yellowstone County Sheriff's Office.

Police scoured all of the routes between the rural property and Billings but there was no sign of Collin. The property is near the Winding Pryor Creek that is obscured by brush. “We’re going to look at maybe concentrating a little more on the water down there. There's a possibility that he could have stumbled.”

Collin’s family will assist in the search in the coming days. “We just want to be here and help with the search,” said Julia Collin. We brought pictures. If we have to make posters and knock on every door, we will.”

His family says Collin is familiar with the region as the oil & gas engineer attended school in Montana and works in the United States on a regular basis.

With files from CTV's Brad MacLeod