DANNEMORA, N.Y. -

The two killers who cut their way out of a maximum-security prison apparently used tools routinely stored there by contractors, taking care to return them to their toolboxes after each night's work so that no one would notice, a prosecutor said yesterday.

District Attorney Andrew Wylie also said that Joyce Mitchell, the prison tailoring shop instructor charged with helping the men escape, had agreed to pick them up in her car and drive off with them but backed out at the last minute because she still loved her husband and felt guilty for participating.

"Basically, when it was go-time and it was the actual day of the event, I do think she got cold feet and realized, 'What am I doing?' " Wylie said. "Reality struck. She realized that, really, the grass wasn't greener on the other side."

Wylie said there was no evidence the men had a "Plan B" once the getaway driver backed out, and no vehicles have been reported stolen in the area.

That has led searchers to believe the men are still near the Clinton Correctional Facility in Dannemora, where the manhunt was in its ninth day yesterday, with hundreds of law enforcement officers slogging through mosquito-infested woods, fields and swamps close to the Canadian border for Richard Matt and David Sweat.

At the same time, Gov. Andrew Cuomo cautioned that for all anyone knows, the convicts could be in Mexico by now.

Wylie said it apparently took a long time for the killers to complete their plan, working methodically between midnight and 5 a.m. over many nights.

"They had access, from what we understand, to other tools left in the facility by contractors under policy and were able to open the toolboxes and use those tools and then put them back so nobody would notice," the prosecutor said. He also said the men had been scouting out the tunnel system under the prison at night for the best way get out.

Workers yesterday welded shut a manhole at the base of a wall on the side of the prison where the two men escaped.