DANNEMORA, New York -- Authorities have found two sets of footprints at the Mobil gas station in Dannemora, the small upstate New York town where the maximum security prison is located that two killers escaped from, Clinton County District Attorney Andrew Wylie confirmed to CBS News Friday morning.
After law enforcement agents saw the footprints, they brought in bloodhounds who detected the escapees' scents, Wylie said.
He wouldn't comment on reports authorities have obtained surveillance video showing the inmates at the gas station.
That word came the day after New York Gov. Andrew Cuomo said the law will come down hard on any prison system employee found to have helped the killers get out.
"If you do it, you will be convicted, and then you'll be on the other side of the prison that you've been policing, and that is not a pleasant place to be," Cuomo told reporters Thursday.
He also said investigators are "talking to several people who may have facilitated the escape."
David Sweat, 34, and Richard Matt, 48, got out of the 3,000 inmate Clinton Correctional Facility in Dannemora, 20 miles south of the Canadian border, and were discovered missing early Saturday, authorities said.
Police were out in force through the night Thursday into Friday as the search approached the one week mark, reports CBS News correspondent Anna Werner.
"We're looking underneath every rock, behind every tree and inside every structure until we catch these two," New York State Police trooper Jennifer Fleishman told Werner.
More than 500 officers are focusing on a small area at the community of Cadyville, about three miles east of the correctional facility the two inmates escaped from, Werner says.
Law enforcement officials told CBS News senior investigative producer Pat Milton dogs picked up the fugitives' scent there, as well. Investigators also found food wrappers and a foot imprint believed to have been from one of the men, but it's unclear when the pair may have been at the site. It's within a small section of the much larger Adirondack park that encompasses about six million acres.
Investigators are hoping the men are wet from rain and beginning to feel the effects of being outdoors, Milton reports. They may not have been equipped for outdoor survival because of their apparent plan to have been picked up, allegedly by prison employee Joyce Mitchell, sources told CBS News. According to the law enforcement source, Sweat has back problems and was on pain medicine at the prison.
On Friday, a law enforcement source told Milton that investigators believe the men are still together. Authorities believe that makes it easier to look for them.
Investigators believe they have contained the men within a perimeter in Cadyville that includes miles of extremely difficult terrain as well as empty summer homes and cabins that the men could use, Milton reports.
Investigators are using night vision goggles and thermal imaging to try and locate the men, Milton reports. The thermal imaging equipment is used on helicopters and can detect heat from a body as well as animals, such as deer in the area.
Authorities are also going to houses that are occupied year-round, ringing door bells and checking in on residents, Milton reports.
The Albany Times-Union reported Friday that Mitchell was expected to face charges of helping Sweat and Matt. Wylie told CBS News Friday morning that charges against Mitchell were possible but that nothing has been filed.
The newspaper said Mitchell admitted smuggling in power tools used in the escape and letting the killers use a cell phone. Wylie told CBS News that Mitchell didn't bring the power tools into the prison. The district attorney told CBS News that Mitchell brought contraband into the prison, but he wouldn't say what it was.
Fleishman said the toughest part about for searchers is that, "They're battling the terrain at this point. ... Our folks that are highly skilled in searching are still finding difficulty. There's trees, there's rocks."
On Thursday, the U.S. Customs and Border Patrol stationed in Michigan dispatched a UH-60 Blackhawk helicopter to search from the air.
At a news conference outside the prison Wednesday, New York State Police Superintendent Joseph D'Amico said a prison employee -- identified by sources to CBS News as Mitchell, a training supervisor at the prison tailor shop -- had befriended the killers and "may have had some role in assisting them."
He would not elaborate.
A law enforcement source confirmed to CBS News that the female prison employee allegedly was supposed to pick up the two inmates after they escaped, but she didn't show up. The source said she went to a hospital instead, apparently suffering from a panic attack, Milton reports.
When she got out of the hospital, the source said, she went to authorities and told them of her involvement in the escape plans.
She has been providing some good information to authorities, the source said. But she allegedly did not know the escapees' entire game plan or what they intended to do if she didn't show up to drive them away.
Matt was serving 25 years to life for the 1997 kidnap, torture and hacksaw dismemberment of Matt's 76-year-old former boss, whose body was found in pieces in a river.
Sweat was doing life without parole for his part in the 2002 killing of sheriff's Deputy Kevin Tarsia, who was shot 15 times and run over after discovering Sweat and two accomplices transferring stolen guns between vehicles.