Despite three weeks of drilling and digging that have revealed no signs of life from six men trapped inside a collapsed coal mine, officials said Sunday the search will continue.

Federal and mine company officials said a seventh borehole would be punched into the Crandall Canyon mine and that a special robotic camera would be lowered into a hole drilled during previous efforts to find the men.

The camera is similar to one used to search within the wreckage of the World Trade Center in New York City after the Sept. 11, 2001, terrorist attacks. It can take images in the darkened cavern from about 50 feet away with the help of a 200-watt light, and can travel 1,000 feet from the end of the test hole — a much wider range than previous cameras used in the search efforts in part because of its ability to crawl through rubble, officials said.

"We're very excited about it. The families are thrilled to hear this," said Colin King, a lawyer for the miners' families.

Robin Murphy, director of the Center for Robot Assisted Search & Rescue at the University of South Florida, said her camera's ability to obtain images in the mine was a long shot. She said it was not clear whether the camera would fit all the way down the hole and into the mine, and that debris in the shaft could obscure any images.

"There's mud, there's rocks, there's things that make it unfavorable," Murphy said. "Certainly if we could find any sign of the miners, that would be terrific."

The announcement came a day after crews penetrated the mine with a sixth borehole, finding a debris-filled area too small for the men to survive, officials said.

"There could be no sign of life in such a condition," mine co-owner Bob Murray said Sunday.

Murray said the seventh hole would be drilled into the kitchen area of the mine, an area where miners are trained to flee in case of collapse. "We haven't given up hope," he said.

Murray had previously said the sixth borehole, drilled more than 1,700 feet deep, would be the last before sealing the mine.

Cesar Sanchez, brother of trapped miner Manuel Sanchez, said the prospect of a seventh hole encouraged the families, who had been outraged when told that the search might end.

"It brings the hope back up. We needed that and we're going to keep going until we find these guys," he said.

Murphy said the robotic camera will lowered into either the third or fourth boreholes.

The fourth hole was drilled more than 1,500 feet into the mountain after mysterious vibrations were detected by aboveground monitors for about 5 minutes on Aug. 15, but when that drill broke through three days later, there was silence. Crews spent at least four hours banging on the drill steel and setting off explosives in an effort to get a response, but without results.

Air monitors sent into that area of the mine showed insufficient oxygen to support life.

The Crandall Canyon miners were last heard from about 3 a.m. Aug. 6, just before a thunderous shudder inside the mountain cracked the ribs of the mine and filled passageways with debris, cutting off an exit route. It's never been clear if they survived the cave-in.

Earlier bore holes produced hazy images and air samples so depleted of oxygen as to be unable to support life. Repeated efforts to signal the miners have met with silence.

Horizontal digging through the rubble-filed mine shaft was halted after a second collapse killed three rescuers and injured six others Aug. 16.

Federal Mine Health and Safety Administration officials say the instability of the mountain makes it too risky to resume underground digging or to drill a hole widen enough to send a manned rescue capsule into the mine.

Seismologists describe the mountain as crumbling in upon itself, bursting support pillars as it shifts in a phenomena known as mountain bumps.

MSHA officials have not specifically said they'll close the mine, but have grown increasingly pessimistic about the chances of finding the men alive or even recovering their bodies.