DANNEMORA, N.Y. — More than a month before two killers escaped from a maximum-security prison in far northern New York State last weekend, a worker there who befriended them provided them with some of the tools to do the deed: hacksaw blades, chisels, a punch and a screwdriver bit, according to criminal complaints.

That worker, Joyce E. Mitchell, 51, of Dickinson Center, N.Y., was arrested on Friday and charged with promoting prison contraband in the first degree, a felony, and criminal facilitation in the fourth degree, a misdemeanor.

Appearing late Friday night in a Clinton County courtroom in Plattsburgh, N.Y., east of Dannemora, Ms. Mitchell — slight, blonde and looking weary — pleaded not guilty. She will be held in jail until her next court appearance, which is set for Monday.

Ms. Mitchell, a civilian employee at the prison, had been under surveillance after being identified by the authorities soon after the escape as a possible accomplice, perhaps as the pair’s planned getaway driver. But she had sought hospitalization at about the same time as the escape, complaining of a panic attack, the authorities said.