A manhunt for the remaining escapee from a New York state maximum security prison has intensified, officials say.
Almost 1,200 federal, state and local law enforcement officers are looking into vehicles at roadblocks and searching dense woods in upstate New York for David Sweat, a convicted killer.
"He's been on the run now for three weeks," Franklin County Sheriff Kevin Mulverhill said of Sweat. "He's tired. He's fatigued. He's hungry. He's going to make a mistake."
Richard Matt, the other convicted murderer, was shot and killed by police in the woods in the town of Malone a few miles from the Canadian border on Friday.
Police have continued search for the other one, but, as of Saturday, there was no sight of Sweat, and bloodhounds have not been able to pick up his scent.
There have been "no sightings ... no real credible leads," Mulverhill told CNN. "The state police do believe they have some evidence that indicates he is within that hard perimeter."
The search covers a perimeter of about 22 square miles along State Route 30 between County Route 41 in Malone and County Route 26 in the town of Duane.
The state police said they were conducting grid searches until the perimeter is cleared.
"I don't think the availability of cabins within this perimeter is the same as what they've had until they've gotten to this point," Mulverhill said.
Authorities are declining to explain why they presumed Sweat was still in the general area where Matt was shot and killed.
The two murderers broke out of Clinton Correctional Facility in Dannemora, New York, 22 days ago.
Matt was in jail for kidnapping, torture and hacksaw dismemberment of his former boss in 1997. Sweat was in prison for killing a sheriff's deputy.
AT/HRJ