(ABC News) -- Israel Keyes, the Alaskan man who confessed to seven murders before killing himself in a jail cell, told police that he traveled the country to find victims and buried caches of weapons, money and tools for disposing of bodies to use in future crimes.
The FBI also released an ominous list of 35 trips Keyes made around the U.S., Mexico and Canada over the last eight years.
Keyes, 34, the owner of an Anchorage construction company, was in jail charged with the February murder of Samantha Koenig, 18. While in jail he had been confessing to at least seven other killings in Washington, New York and Vermont. He was found dead in his Alaska jail cell on Sunday in an apparent suicide.
Investigators are now piecing together a deadly puzzle that is uncovering a macabre lifestyle of Keyes traveling to kill simply because he "liked to do it," prosecutors said.
"In a series of interviews with law enforcement, Keyes described significant planning and preparation for his murders, reflecting a meticulous and organized approach to the crimes," the Anchorage FBI office said in a statement.
The FBI has released a timeline of Keyes' travels that showed nearly three dozen trips between 2004 and 2012. The destinations of the trips are vague, described only by U.S. region in most cases, but span the entire country, including Hawaii. There are also trips to Canada and Mexico listed.
"Keyes also admitted traveling to various locations to leave supplies he planned to use in a future crime. Keyes buried caches throughout the United States," the FBI said.
Authorities have already recovered two caches, one in Alaska and one in New York, that contained money, weapons and items for disposing of bodies. Keyes indicated that there were other supply boxes buried across the country.
He funded his travel with the proceeds from bank robberies, authorities said.
"Investigators believe that Keyes did not know any of his victims prior to their abductions," the FBI said. "He described several remote locations that he frequented to look for victims--parks, campgrounds, trailheads, cemeteries, boating areas, etc."
Keyes told authorities that his victims received little if any media attention when they disappeared. Authorities said that "based on his own research," Keyes said that one of his victims had been recovered, but the death was ruled accidental. Investigators said they have not identified the victim or location of that alleged crime.
Before his death, Keyes indicated that, in addition to Koenig and a Vermont couple, he killed four people in Washington State and one person in New York, but did not give the victims' names, authorities said.
"It was not unusual for Keyes to fly into an airport, rent a car, and drive hundreds of miles to his final destination," the FBI said.
That is precisely what Keyes did in the murder of Bill and Lorraine Currier in Essex, Vt., last year. He flew from Alaska to Chicago in June 2011. He rented a car in Chicago and drove to Vermont where he spent three days looking for his next victims and planning the slaying.
"When [Keyes] left Alaska, he left with the specific purpose of kidnapping and murdering someone," Chittenden County State Attorney T. J. Donovan said at the press conference. "He was specifically looking for a house that had an attached garage, no car in the driveway, no children, no dog."
The Curriers, unfortunately, fit all of Keyes' criteria. He spent three days in Vermont before striking. He even took out a three-day fishing license and fished before the slayings.
Keyes abducted the couple from their home and murdered them in an abandoned barn he had located before breaking into the Curriers' home. After binding the couple with plastic cuffs, the beat the husband with a shovel and then shot him. The wife was raped and strangled.
"By all accounts, [the Curriers] were friendly, peaceful, good people who encountered a force of pure evil acting at random," an investigator said at today's news conference. Authorities called the ongoing investigation a "huge case, national in scope."
One of the most chilling aspects of Keyes' operation is the lack of any motive other than pleasure.
"He provided some motivation, but I don't think it's really [possible] to pigeonhole why he did this," Tristram Coffin, U.S. Attorney in Vermont, said at a news conference today. "He described to investigators that this was a volitional act of his. He wasn't compelled by some uncontrollable force, but it was something that he could control and he liked to do it. Why someone likes to act like that, nobody knows."
Keyes had been facing a March trial in Anchorage federal court--and possibly the death penalty--for the killing of Koenig.
Samantha Koenig was last seen Feb. 1 on surveillance video that showed her leaving the Common Grounds Espresso stand in Anchorage with an armed man. All of the coffee stand's cash was also missing.
Keyes was arrested in Lufkin, Texas, March 16 after he used Koenig's debit card. The FBI contends Keyes killed Koenig less than a day after she was kidnapped. Her body was recovered April 2 from an ice-covered lake north of Anchorage.
Police and the FBI spent hours talking to Keyes in the months after his arrest and he was cooperating, talking to investigators as recently as Thursday.
Authorities wouldn't say how Keyes killed himself, only that he was alone in his cell. An autopsy will be conducted.
Keyes owned a construction company in Anchorage. According to the website for Keyes Construction at the time of his arrest, Keyes worked in Washington State in the mid-1990s and then served three years in the Army infantry, stationed in Fort Lewis, Fort Hood, and Sinai, Egypt. According to the site, he then worked from 2001 to 2007 for the Makah Tribal Council in Neah Bay, Wash., before moving to Alaska.
The FBI is asking for the public's assistance with any information about Keyes' travels in order to identify additional victims. They ask that anyone with information contact the FBI at 1-800-CALL-FBI.