PLATTSBURGH, New York (CNN) -- Richard Matt, one of two escaped murderers from an upstate New York prison, has been shot and officers involved in a nearly three-week manhunt are pursuing fugitive David Sweat, a law enforcement source briefed on the investigation said Friday.

Escaped murderers Richard Matt and David Sweat may be headed to Canada, a New York State Police spokesman said Friday.

Investigators are conducting DNA tests on potential new evidence, a source close to the investigation said.

A reported burglary led police to a cabin Thursday in the town of Malone, New York, State Police spokesman Beau Duffy told CNN.

Conclusive evidence was found in the cabin, which is being tested, he added.

"There has been no definitive credible sighting based on a physical description to pair with the evidence, but we're certain that the evidence is conclusive," State Police Maj. Charles Guess said Friday at a news conference.

More than 1,100 law enforcement officers are pursuing new leads with a "high degree of confidence," Guess said.

Two prison employees have been charged in connection with the men's elaborate June 6 breakout, and the accusations against them highlight a series of apparent security lapses.

Investigators from the New York State Inspector General's Office are looking into possible breaches of security protocols that allowed Matt and Sweat to escape, setting police on a vast and costly manhunt for the past three weeks.

Other agencies are conducting investigations at the prison.

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