Authorities collected several items on Saturday from a hunting cabin in Owls Head, New York, including prison-issue underwear, a law enforcement source said.
When the owner of the hunting cabin arrived to check on the place earlier Saturday, the owner saw signs of people being inside, two officials briefed on the case told ABC News.
The owner shouted and then saw at least one person bolt from the cabin, according to officials.
When police arrived they saw food left behind, officials said.
The food was then collected by investigators, from which positive DNA samples were confirmed from both suspects, an official briefed on the search said.
New York State Police Maj. Charles Guess said at a news conference today the DNA tests reached a "conclusive determination." While Guess confirmed that "specific items" were recovered from the cabin, he did not elaborate on the items.
New York Sen. Chuck Schumer, who has been briefed on the case by participating federal authorities, said today this is the closest searchers have come in 11 days.
"The trouble is the terrain around this cabin is very, very rough terrain. It's hard to do a perimeter," Schumer told ABC's New York station WABC. "But they have hundreds of law enforcement people trying to work on the case and make sure that they find him. This is the closest they've come in the 11 days but they are still a ways from catching him."
The Owls Head campsite lead has sparked increased police presence in the area -- authorities have set up road blocks and are searching every car that goes by.
Police said they have followed more than 2,000 leads so far.
Earlier, an increased police presence was reported in Friendship, New York, in the southern part of the state, after a witness reported a possible sighting of the men on Saturday.
A witness called police saying she spotted two men who fit the description of Matt and Sweat on a railroad line along Route 20 in Friendship near the Pennsylvania border Saturday at 1:16 p.m., state police Major Michael Cerretto said at a news conference.
Matt was serving 25 years to life after he was convicted of kidnapping and beating a man to death in 1997. Sweat was serving a life sentence after he was convicted of killing a Broome County sheriff's deputy in 2002.