Officials extinguished nearly all hope of finding any of the six miners alive on Sunday, nearly two weeks after the men were trapped in a violent collapse deep within the Crandall Canyon mine.
The latest results from a fourth hole drilled more than 1,500 feet into the mountainside found the air quality could not sustain life, said a top executive of the company that co-owns the mine in central Utah.
Rob Moore of Murray Energy Corporation says: quote "It's likely these miners may not be found."
It was a marked shift in tone after days of public, unflinching optimism that the men would be rescued.
There has been little evidence that the miners survived the initial August 6th collapse.
Workers have gained limited access to the mine through four boreholes in which video cameras and microphones were placed.
Rescuers banged on a drill steel and set off explosives Saturday, hoping to elicit a response from the men.
Their efforts were met with silence.
Engineering experts from around the nation gathered at the mine Sunday to try to figure out a safe way of reaching the missing men.
Underground tunneling has been halted since a mountain "bump" Thursday killed three rescuers and injured six others.