With one escaped prisoner shot dead, police hoped that the other one still on the run in a remote New York forest will quickly be worn down by lack of sleep, little food and another night of rain.
Richard Matt, who once vowed never to be taken alive, was fatally shot during an encounter with border patrol agents on Friday, almost three weeks after he and David Sweat staged an elaborate breakout from a maximum-security prison.
More than 1,200 searchers remained focused intensely on 22 square miles of thick forests and heavy brush around where Matt was killed.
"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," Franklin County Sheriff Kevin Mulverhill said of Sweat.
"He's fatigued, tired, and he's going to make a mistake."
Sweat also could have an even tougher time now without someone to take turns resting with and watch his back, said Clinton County Sheriff David Favro.
"And I'm sure fatigue is setting in for him as well, knowing the guy he was with has already been shot."
There were dramatic developments in the manhunt on Friday when a person towing a camper heard a loud noise and thought a tyre had blown.
Finding nothing, the motorist drove on before looking again and finding a bullet hole in the trailer. A tactical team responding to the scene of the gunshot smelled gunpowder inside a cabin and saw evidence that someone had fled.
A noise, perhaps a cough, ultimately did Matt in. A border patrol team discovered the escaped prisoner, who was shot after failing to obey a command to raise his hands.
Matt had a shotgun. He and Sweat apparently had been relying on the 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.
Sweat, 35, was serving a sentence of life without parole in the killing of a sheriff's deputy. Mr Mulverhill said investigators believe he may be armed.
While there have been no confirmed sightings of Sweat since the escape, police said investigators saw a second set of tracks near where Matt was shot. Searchers hoped for one last break before heavy rains forecast for today come in.
Ultimately, how the chase ends is up to Sweat, Mr 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."