He spent almost three decades living in the forests of Maine, US.
He survived brutal winters, broke into houses and avoided detection by police and neighbours.
Christopher Knight, also known as the North Pond Hermit, now faces another big challenge: reintegrating into society.
He pleaded guilty on Monday to 13 counts of burglary and theft, and was admitted into a special court programme that allows him to be released from jail to live and work in the community under supervision.
Police have said the 47-year-old may have been responsible for as many as 1,000 burglaries while living in the woods of the central Maine town of Rome for 27 years before his arrest in April, AP reported.
Knight's lawyer Walter McKee said he believes Knight is ready to be free, but acknowledged that he likely faces big hurdles after spending so many years isolated from the community.
"A lot has changed in 30 years," Mr McKee said.
"And going from a life of solitude to being part of our modern society would be a challenge for anyone."
As to what compelled Knight to vanish from his home, Mr McKee said: "I think it's something we may never know."
In a bid to make his forest camp invisible from the air, Knight told Maine State Trooper Diane Perkins-Vance that he never lit a fire, even on the coldest nights.
He covered shiny surfaces, such as his metal trash cans, with moss and dirt, and painted green a clear plastic sheet covering his tent.
Knight told Ms Perkins-Vance his campsite faced east and west to make the best use of the sun, and that he had been watching one particular mushroom grow for the past four years.
She told local newspaper Morning Sentinel: "He claims he hadn't had a conversation with another human being since the mid-1990s, when he encountered someone on a trail.
"I was the first person he talked to since the 1990s."
Shaving without the aid of a mirror, Knight told police that he used a nearby pond to get his reflection.
"He hasn't seen himself in the mirror for well over 20 years," Sergeant Terry Hughes of the Maine Warden Service said.
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