Officers scouring dense and boggy woods for a surviving escaped killer took floodlights into the search area overnight, and others carrying rifles manned checkpoints and examined vehicles, opening trucks and peering into windows.

Franklin County Sheriff Kevin Mulverhill said late Saturday tips continued to pour in and he was optimistic David Sweat would be captured, perhaps within 48 hours.

"It's going to be one of those phone calls that turns this case around," he said.

Richard Matt — who once vowed never to be taken alive — was fatally shot Friday during an encounter with border patrol agents about 30 miles west of the prison he escaped from with Sweat on June 6. Sweat remained on the lam early Sunday, and about 1,200 searchers focused intensely on 22 square miles encompassing thick forests and heavy brush around where Matt was killed.

Police hoped the solo escapee would finally succumb to the stress of little sleep, scant food and biting bugs.

"Anyone in the woods and on the run from the law so to speak is not getting a full eight hours sleep, they're not eating well and they have to keep moving," Mulverhill said. "He's fatigued, tired, and he's going to make a mistake."

Sweat could have an even tougher time now without someone to take turns resting with and to watch his back, Clinton County Sheriff David Favro said.

"Now it's a one-man show and it makes it more difficult for him," Favro said. "And I'm sure fatigue is setting in for him as well, knowing the guy he was with has already been shot."

The manhunt broke open Friday afternoon when a person towing a camper heard a loud noise and thought a tire had blown. Finding there was no flat, the driver drove eight miles before looking again and finding a bullet hole in the trailer. A tactical team responding to the scene of the shot smelled gunpowder inside a cabin and saw evidence that someone had fled out the back door.

A noise — perhaps a cough — ultimately did Matt in. A border patrol team discovered Matt, who was shot after failing to heed a command to raise his hands.

Matt had a 20-gauge shotgun that was believed to have been taken from another cabin. The pair had apparently been relying on the remote region's many hunting camps and seasonal dwellings for supplies.

Matt, who turned 49 the day before he died, was serving 25 years to life at Clinton Correctional Facility for the killing and dismemberment of his former boss. Local residents were relieved that one killer was no longer roaming the woods, but the constant commotion of speeding police cruisers and helicopters pointed to the continued danger.

"Half the threat is taken care of, but obviously David Sweat is on the loose," said Matt Maguire, who was waiting for a police escort to pick up some clothes from his house inside the search area. Maguire and his fiancee decided a week ago to stay with nearby relatives.

Sweat, 35, was serving a sentence of life without parole in the killing of a sheriff's deputy in Broome County in 2002. Mulverhill said investigators believe he may be armed.

Matt and Sweat used power tools to saw through a steel cell wall and several steel steam pipes, bashed a hole through a 2-foot-thick brick wall, squirmed through pipes and emerged from a manhole outside the prison.

While there have been no confirmed sightings of Sweat, police said investigators saw a second set of tracks near where Matt was shot.

Ultimately, how the chase ends is up to Sweat, Mulverhill said.

"If he's willing to surrender to law enforcement then we'll place him in handcuffs and we'll bring him back into custody," he said.

"If he chooses to resist or he chooses not to comply, then the results are his."

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Associated Press writers Jim Fitzgerald in New York City and Michael Hill in Albany, New York, contributed to this report.