HUNTINGTON — Despite three weeks of drilling and digging that have revealed no signs of life from six men trapped inside a coal mine, an attorney for families of the miners said Sunday the search would continue.

Colin King, lawyer for the families, said federal and company officials told him and the miners' relatives that a robotic camera was going to be lowered into a hole drilled during previous efforts to find the men.

The camera, similar to one used at the World Trade Centers in New York after the Sept. 11 attacks, can take images in the darkened cavern from about 50 yards away with the help of a strong light. It also has a much wider range than previous cameras used in the search efforts in part because of its ability to crawl through rubble, he said.

The announcement was made a day after crews pierced the mine shaft with a sixth borehole to find a debris-filled area too small for the men to survive, according King and the Web site of the federal mine safety agency.

Federal and company officials said they would hold a news conference at 3 p.m. MDT Sunday to discuss the search efforts.

King said the robotic camera was to be dropped into the fourth borehole, which was drilled more than 1,500 feet into the mountain. That was done after mysterious vibrations were detected by aboveground monitors for about 5 minutes Aug. 15. But when the 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. A microphone picked up no noise.

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

King said Sunday that a mine company lawyer also told families that a seventh borehole was under consideration. That one might be drilled into the kitchen area of the mine, an area where miners are trained to flee in case of collapse.

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, cutting off an exit route and filling the shaft with debris. It's never been clear if they survived the cave-in.

Earlier bore holes showed hazy images and some 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 underground mine shaft to reach the six 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 more than 1,500 feet into the mine.

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

Despite promises made to the men's families to find the six miners dead or alive, mine co-owner Bob Murray had said the sixth borehole drilled more than 1,700 feet deep would be the last before sealing the mine.

"If we don't find anybody alive, there is nowhere else that anyone in MSHA or our company would know anywhere to drill," Murray said last week.

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.