Story highlights

NEW: A source says the escapees planned to kill the husband of prison worker Joyce Mitchell

An official says the search for two convicted murderers has gone cold since last week

CNN  — 

Have authorities lost the trail of two convicted murderers who broke out of a New York prison?

A New York state official briefed on the investigation told CNN on Monday that the search has gone cold since last week, when investigators found what they believe were several human tracks and a bloodhound possibly picked up a scent.

There were promising clues last week, the official said, but since then, authorities have come up with little to point them toward the fugitives.

Ten days into their search, authorities seem no closer to capturing Richard Matt and David Sweat. Despite the efforts of 800 law enforcement officials popping open trucks, peering into cars and scouring heavily wooded areas, New York’s governor acknowledged over the weekend that the pair could be almost anywhere.

Clinton County Sheriff David Favro said Monday that they could still be in the woods near the prison in upstate New York – or long gone.

And the prosecutor whose office brought charges against prison tailor Joyce Mitchell for allegedly aiding the escape said authorities can’t say for sure whether anyone else was involved or whether Mitchell knows more than she’s letting on.

Meanwhile, the leads keep piling up – more than 870 of them so far, according to New York State Police.

They involve a mishmash of far-flung places: Vermont, Mexico, even a few miles from the Clinton Correctional Facility, the maximum-security prison in Dannemora, New York, from which Matt and Sweat escaped on June 6.

Details about the fugitives’ whereabouts may be scarce, but new details are emerging about Mitchell’s relationship with the prisoners and the escape plot that one source says could have taken a deadly turn.

Source: Escapees plotted to kill husband

Matt and Sweat had a plan to kill the prison tailor’s husband, a source with detailed knowledge of the investigation said. It’s unclear why, when they intended to do it and how much Mitchell actually knew about that plan.

Investigators are looking into whether the two inmates threatened Mitchell to force her to help in the escape, the New York state official told CNN.

Investigators believe Mitchell began getting cold feet executing the plan but possibly had agreed to be the getaway driver because of threats to her and her husband, the official said.

Mitchell was having a sexual relationship with Matt, the source with detailed knowledge of the investigation said. And she’d also been investigated in the past for an inappropriate relationship with Sweat that led corrections officials to move him out of the tailor shop and keep them separated, Clinton County District Attorney Andrew Wylie said.

The prisoners might have been manipulating Mitchell from as far back as 2013, when the trio met, according to the prosecutor.

Mitchell appeared in court Monday for a planned preliminary hearing, but that provided no answers.

Wearing a black-and-white-striped prison jumpsuit and with her hands shackled to her waist, she didn’t say anything during the brief hearing.

Her attorney waived her preliminary hearing after a more than two-hour delay that was needed after her first court-appointed attorney had to drop out because of a potential conflict of interest.

Mitchell has been in jail since last week, accused of helping the pair break out of their cells, and she will remain there unless she posts a $220,000 bond or $110,000 in cash.

She allegedly supplied the tools

Mitchell supplied the inmates with various tools, including hacksaw blades, chisels, a punch and a screwdriver bit, according to court records.