It took at least three years for authorities to identify him from fingerprints lifted from vacation homes near Zion National Park.
Now, they just have to catch him. Knapp remains somewhere in roughly 1,000 square miles of wilderness, a virtual ghost in the woods stocked with stolen gear, food and guns.
"This guy is probably about as true a survivalist as Davy Crockett," Supervisory Deputy U.S. Marshal Michael Wingert told The Associated Press.
Authorities have so far revealed little about the 44-year-old Knapp or how he ended up wandering the mountains of southern Utah. They identified him Tuesday and asked the public for help in finding him.
Knapp has family members in Moscow, Idaho, but phone messages left for them Tuesday evening were not returned.
Just last week, detectives in Iron County said investigators hadn't made a definite identification but were getting close. However, court records indicate charges were filed against Knapp in neighboring Kane County about three weeks ago as the key suspect in the serial burglaries.
According to the records filed Jan. 27, Knapp's fingerprints lifted from one cabin in 2009 were matched on Jan. 20 to records from a 2000 theft arrest in California. The records indicate only that he has been convicted previously on charges of assault with a dangerous weapon and burglaries.
Wingert said Knapp "dropped off everybody's radar in 2003 and nobody has heard from him since."
"He just dropped off the face of the earth," Wingert added, speculating that Knapp was "fed up with civilization."
He now faces multiple counts of burglary and a weapons charge.
In a statement Tuesday evening, the Iron County Sheriff's Office said tips from the public and forensic evidence linked Knapp to the crimes.
"This suspect is known to be armed and could be possibly dangerous if cornered," the statement read, adding that his identification was the result of "good old-fashioned investigative work, along with tips provided by the public."
"We believe Mr. Knapp is our guy," Wingert said.
Iron County Sheriff's Detective Jody Edwards said last week that investigators were still scouring for clues. He indicated authorities were getting close to solving the case after they got the first pictures of the suspect from a motion-triggered surveillance camera outside a cabin. The photos taken sometime in December showed a sandy-haired man in camouflage on snowshoes, a rifle slung over his shoulder.
However, Edwards would say only that "we're very close to making a positive ID on him."
"We just got to catch this guy," he said.
Edwards has been working the case since 2007. He didn't return a call seeking comment Tuesday evening.
Authorities say Knapp has eluded capture for more than five years, breaking into remote cabins in winter, living in luxury off hot food, alcohol and coffee before stealing provisions and vanishing into the woods with guns and supplies.
This undated photo provided by the Iron County Sheriff's Office shows , a remote camp littered with supplies and trash in the southern Utah wildness near Zion National Park. Authorities believe the camp was left behind by a suspect in more than two dozen burglaries of mountain cabins over an area of roughly 1,000 square miles for the past five years. (AP Photo/Iron County Sheriff)
Investigators have chased dozens of leads, to no avail.
In recent weeks, it took detectives an entire day to reach a remote cabin after getting a report that lights had been seen on inside overnight. It turned out they were solar-powered lights on the porch, and the cabin was empty — another dead-end.
Their break came in January with the fingerprint match.
While there have been no violent confrontations, detectives have called him a time bomb. Over the years, he has left some cabins tidy and clean, while others he has practically destroyed, even defecating in a pan on the floor in one home.
Lately he has been leaving the cabins in disarray and riddled with bullets after defacing religious icons, and a recent note left behind in one cabin warned, "Get off my mountain."
In the Jan. 27 court filing, authorities said Knapp had left behind even more threatening notes aimed at law enforcement.
"Hey Sheriff ... Gonna put you in the ground!" read one note.
Cabin owners are panicked. Many said they were carrying their owns guns and had grown to wonder who might be sleeping in their beds during winter.
"He could stand in the trees and pop you off and no one would know who killed you," cabin owner Bruce Stucki said last week.
When alerted of the news Tuesday, a relieved Stucki simply said, "Wow."
"That's wonderful that they know him," he said. "Now they need to get him in custody."
From the beginning, the suspect's lore grew, leading to theories that he might have been two separate men on the FBI's Most Wanted List or possibly a castaway from the nearby compounds of the Fundamentalist Church of Jesus Christ of Latter Day Saints, the polygamous sect run by jailed leader Warren Jeffs.
Early on, investigators thought his unattended summer camps they came across during their search were left behind by "doomsday" believers preparing for some sort of apocalypse because of the remote locations and supplies like dozens of guns, radios, batteries, dehydrated food and camping gear.
They now have a name, but the man remains in the mist.
"He's scaring the daylights out of cabin owners. Now everyone's packing guns," said Jud Hendrickson, a 62-year-old mortgage adviser from nearby St. George who keeps a trailer in the area. "We feel like we're being subject to terrorism by this guy."