NEW YORK (AFP) - A female prison worker plead not guilty on Friday to allegedly helping two convicted killers in New York state escape by smuggling tools to them, US media reported, as police stepped up their week-long manhunt.
Swarms of state, local and federal agents combed thick woods east of the Clinton Correctional Facility, which Richard Matt, 49, and David Sweat, 35, busted out of, using power tools to cut their way out, before crawling along pipes and out to freedom via a manhole.
Investigators have focused on who helped Matt, who was convicted of dismembering his 76-year-old former boss, and Sweat, who shot dead a sheriff's deputy.
Joyce Mitchell, 51, who worked at a tailoring shop at the sprawling prison, was arrested and charged on Friday with "promoting prison contraband" and criminal facilitation.
Mitchell was presented with the charges in court during an arraignment in which she appeared handcuffed and visibly nervous.
CNN and other US media reported that she pleaded not guilty.
Mitchell "provided some form of equipment or tools" that allowed the two murderers to escape, the Clinton County district attorney Andrew Wylie earlier told CNN.
Mitchell's arrest was "one large piece of the puzzle" in the hunt for the duo, Major Charles Guess of New York State Police told a press conference, adding: "We have a message for David Sweat and Richard Matt. We're coming for you and we will not stop until you are caught."
- 'Dangerous and desperate' -
US media reported that Mitchell's husband, another prison employee, was also being investigated for possible involvement in a search that has captivated America.
He had not been charged and was not in custody, Guess said, adding that wet weather and the rolling woodlands and hills where the search is focused were complicating the hunt.
But that might also slow the killer pair's progress, too, he cautioned.
"If they have not escaped the area or they have not availed themselves of shelter, we've got to assume they're cold, wet, tired, and hungry," he said.
"I would advise and remind the community and the residents that that makes these individuals even more dangerous and desperate."
Authorities "do not have any conclusive evidence that either of the inmates has left this area," he added, referring to the land around the town of Plattsburgh, about 24km east of the prison.
Hacksaw blades, drill bits and two pairs of spectacles with attached lights were among the items Mitchell allegedly gave the convicts, CNN quoted two unnamed law enforcement sources as saying.
Officials have suggested that Mitchell may have been charmed by Matt and Sweat, and agreed to pick them up by car from the manhole where they emerged in the early hours last Saturday.
Instead, she changed her mind and checked into a hospital - reportedly suffering from a panic attack.
The Wall Street Journal reported that Mitchell had also been under investigation in the last year for allegedly forming a relationship with Sweat while they worked together in the prison tailoring shop.
There was not enough evidence to take action, but Sweat was pulled out of the shop, the newspaper reported.
- Search intensifies -
Police said the search continued along state highway 374 and a section of the highway would remain closed until the search was completed. Local schools were also closed until Monday to allow the manhunt to continue unimpeded.
Police said that more than 800 officers - an increase of 300 personnel - were mobilized, including FBI agents and forest rangers, backed by K9 units and helicopters, chasing more than 700 leads.
One local newspaper, the Press-Republican, said dogs had picked up the convicts' scent on Wednesday and traced it from outside a convenience store and gas station through the woods.
There is a US$100,000 (S$134,369) reward for information leading to the duo's arrest, and the public has been warned to call 911 immediately if they spot anything suspicious and not to approach either man.
Matt, 1.83-m tall with multiple tattoos, was serving a sentence of 25 years to life for the 1997 kidnapping and dismembering of his former boss in a 27-hour ordeal. He fled to Mexico after the murder and killed an American, before being sentenced to 20 years and extradited back to New York.
Sweat was serving a life sentence without parole for murdering a sheriff's deputy in New York state in 2002 when he was 22.
The pair's escape has been likened to Hollywood movies such as "The Shawshank Redemption" or "Escape from Alcatraz." After cutting through walls and crawling through an underground pipe system, they left behind a note saying "Have a Nice Day".