Authorities have ended the search for a Twin Cities father and son who remain missing more than a week after they walked into the snow-covered Colorado wilderness.

The decision, an emotionally wrenching development for the family and searchers, was made Wednesday because rescue workers have found no sign of Damian McManus, 51, of St. Louis Park, and his 18-year-old son, Evan, who haven't been heard from since last Wednesday.

In a Facebook post, the family expressed its "deep gratitude" to the search teams. "They have done all they can and they believe that they could not have survived," they posted.

"The die was cast in this case long before we were alerted to the situation," said Steve Wilson, spokesman for the Alpine Rescue Team. "We weren't called about this until Sunday, and by then they already had been out there four or five nights."

No one knew the two were missing until they didn't return to Minnesota on Saturday as expected. Their car was found Sunday in a parking lot near Echo Lake, about two hours west of Denver.

'All a mystery'

"There's no telling what could have happened to them," Wilson said. "All we know is that last Wednesday they were in this general area. Where they went from there and what they did is all a mystery. … It's hard to say if they're dead or alive, or they're there or somewhere else. We just don't know."

The father and son had gone to Colorado for a spur-of-the-moment spring break trip. They were last heard from when Evan sent a message on Wednesday to his girlfriend.

On Sunday, authorities began the daunting task of searching a vast wilderness at the base of the 14,000-foot Mount Evans with no clues to guide them. In the last two days of the search, searchers trekked throughout an area where signals from the father's and son's cellphones had been detected last Wednesday.

"Unfortunately, over the last four days, we haven't found any signs of them at all," Wilson said. "We're out of ideas. We're out of clues. We have nothing to go on at this point. There's really no other choice at this point."

A scent dog, a helicopter and dozens of trained search volunteers on skis and snowshoes scoured the wilderness. Deep snow, high winds and clouds hampered the search.

For much of the week that Damian and Evan have been missing overnight temperatures dropped below freezing.

Authorities also searched an area where avalanches have occurred but found no signs of recent slides or the McManuses. Searchers also checked a steep area where they might have fallen, Wilson said.

A difficult decision to make

Ending a search without rescuing someone or finding a body is difficult decision, he said.

"It's one of the hardest things we have to face," he said. "Not having the closure, always second-guessing what we did, how we did it. … We know how tough it is for us to deal with this, it's unimaginably worse for the family members. We go out there to help someone and make a difference. We didn't make a difference to the two missing people this time. We did everything we could and that's all we could do in this case. It's tough."

Mary Lynn Smith • 612-673-4788