DANNEMORA, N.Y. – The search for two escaped killers from New York’s top-security prison continued locally Monday 10 days after they fled, but Gov. Andrew Cuomo admitted they could be long gone from the Adirondack Mountain area.

“We don’t know if they are still in the immediate area of if they are in Mexico by now,” said Cuomo. “We’re following every lead to the best we can.”

Authorities have received scores of tips on possible sightings of fugitives Richard Matt, 48, and David Sweat, 35. Most of them were local but some extended to Mexico, where Matt once eluded a U.S. murder warrant. More than 800 law enforcement officials are participating in the search.

Clinton County District Attorney Andrew Wylie said because prison worker Joyce Mitchell bailed on a plan to drive the convicts from the scene of their June 6 escape, authorities believe they are still on foot and hiding in the heavily wooded terrain east of the prison.

Mitchell has been charged with helping the killers escape by providing them with some of the tools used to cut holes in their adjoining cells, break through a brick wall and cut into a steam pipe that led beneath the prison walls to an outside manhole. Wylie said Sunday she had a change of heart as the getaway driver but she had planned to flee with them to places unknown in a Bonnie and Clyde-type adventure.

“The three of them were going to move on together,” said Wylie. “That was the plan. She got cold feet and realized, ‘What am I doing?’ Reality struck.”

Mitchell befriended the killers as their supervisor in the prison’s tailoring shop. She has pleaded not guilty to being an accomplice to their escape and is due back in court Monday.

Wylie said the investigation into the escape has determined that Matt and Sweat worked on their escape plan for weeks before they broke out of the prison, using power tools at night from a construction site in the prison, then returning them to their tool boxes so they would not be noticed as missing.

Wylie said the inmates also became familiar with the inner passageways of the prison, including the maze of pipes and electrical wires, during the weeks leading up to the escape.

Mitchell is accused of providing them with hacksaw blades, chisels, a punch and a screwdriver bit. She first became acquainted with Matt and Sweat in 2013 as their sewing instructor, and later was suspected of having a relationship with both of them. But an internal investigation failed to turn up sufficient evidence of any wrongdoing.

Sweat was serving a life sentence without parole for killing a sheriff’s deputy. Matt was doing 25 years to life for kidnapping, torturing and dismembering his former boss. Matt also served time in a Mexican prison for killing a man there while hiding out from the U.S. murder charge.