Transcript for America's Most Wanted Eric Frein Still at Large
Now, to a dramatic new development in the manhunt for one of America's most wanted. The someone accused of that deadly ambush on state troopers. A letter from the accused gunman himself. Seen right there in that documentary about a war re-enactment. He's led searchers on a cat and mouse game through the Pennsylvania woods for three weeks now, and now this new letter. Filled with details of what he did that started this all. ABC's Linzie Janis in Pennsylvania. Reporter: Tonight, ABC news has learned police searching for Eric Frein found a handwritten letter detailing how he shot two state troopers. And how he escaped. Authorities say it isn't clean if the letter was left on purpose and it offers no motive. Today, Frein's family declining to speak with us. This, as police patrol the area near the family's home, where less than 24 hours ago, a state trooper thought he spotted the survivalist and war re-enactor seen in this documentary. It's not Vietnam. We're in the middle of Pennsylvania. We're in a revolutionary war fort. Reporter: Hundreds of officers racing to the location Sunday evening. One of the advantages of fall and winter is, the leaves go away. So, Mr. Frein doesn't have a canopy anymore to cover him. Reporter: Investigators say Frein will likely break into one of the hundreds of vacant proper tips in this location. John hornby is surrounded by vacation homes. We'll walk around the building, check all the glass. Reporter: David, this area is also full of abandoned homes, like this one. Police say Frein could use any one of them for shelter from the elements.
This transcript has been automatically generated and may not be 100% accurate.