Huntington, Utah ? Ghostly video images from deep underground showed a tool bag, shards of broken rock, a twisted conveyor belt and dripping water but no signs of life as the arduous search for six missing miners stretched Monday into a second week.

Even as the grainy footage played for reporters, the mine’s co-owner insisted there was reason to believe the miners could be alive – the mine’s roof was intact, there was abundant open space and plenty of drinkable water.

“There are many, many reasons to have hope still,” said Bob Murray, head of Murray Energy Corp. and co-owner of the mine.

On Monday evening, Murray said the pace of digging into the collapsed mine had picked up, with rescuers clearing out about 670 feet of the 2,000 feet of rubble they were expected to encounter in the mine’s main passageway. He said the effort could take several more days.

“The progress underground has picked up substantially,” Murray told The Associated Press after he gave a private briefing for family members.

He had acknowledged earlier that the search, which has been interrupted by additional cave-ins and two 1,800-foot holes that came up empty and prolonged silence from underground, has not gone as smoothly as planned. “Progress is slow – way too slow.”

Meanwhile, memos from an engineering firm revealed concern about structural problems at the mine as early as March, when a different underground area was damaged.

Rescuers were starting to bore a third hole deep into the mine, Murray said. A 2 1/2-inch-wide hole and a nearly 9-inch-wide hole drilled last week have found no sign of life where the miners were working when a collapse hit the Crandall Canyon mine early Aug. 6.

The video was recorded Sunday evening by a camera dropped into a shaft more than 1,800 feet deep. It showed water dripping in front of the lens as light faintly illuminated objects – a chain, a twisted conveyor belt, a tool bag – 10 to 15 feet away.

“We see a lot of open area. We see good height. Space is what they need and we saw a lot of space,” said Al Davis of the federal Mine Safety and Health Administration.

Murray said he believes the tool bag belongs to one of the miners, who may have been hundreds of feet away from the bag while working.

Davis said the view was basically what was seen in earlier attempts with the camera, but with better resolution and better lighting. Still, the camera only saw about 15 feet when it was lowered into the mine overnight.

The new 8 5/8-inch hole was to be drilled to an area to which the miners might have fled after finding escape routes blocked.