The FBI is appealing for information about the travels of a suspected serial killer believed to have murdered up to 15 people over more than a decade before he committed suicide in jail.
Israel Keyes is thought to have murdered at least eight people between 2001 and March 2012 when he was arrested, said special agent Eric Gonzalez, of the FBI's office in Anchorage.
Keyes, who died in prison from apparently selfinflicted wounds last weekend, lived in Washington state from 2001-2007 and then in Alaska.
But he travelled around the country kidnapping, raping and murdering victims, as well as robbing banks, the FBI said.
In preparation for his crimes, he buried caches of supplies in a several locations, including weapons and items to help dispose of his victims' bodies.
The 34-year-old allegedly killed "at least eight, but investigators suspect more," Gonzalez said. He added that from interviews conducted after Keyes' arrest, "their sense was that he possibly killed 12-15 people".
Gonzalez added: "Right now we're looking for information concerning his travels, if anyone may have recognised him."
The FBI appeal, first made on Monday, was already providing some leads. "The media is actually referring cases with similarities to us," Gonzalez said. Keyes admitted murdering four people in Washington state - two victims in 2005 and 2006, and a couple some time between 2001 and 2005. He may have abducted them from another state and brought them to Washington.
"Additionally, Keyes admitted to investigators that, in 2009, he murdered a victim on the east coast and disposed of the body in New York State," the FBI said in a statement. It added that the victim was probably abducted in another nearby state.
In interviews with police, Keyes "described significant planning and preparation for his murders, reflecting a meticulous and organised approach to his crimes".
The FBI continued: "It was not unusual for Keyes to fly into an airport, rent a car and drive hundreds of miles to his final destination."
In preparation for the murder of Bill and Loraine Currier, for example, Keyes took a plane to Chicago and then drove in a rented car across several states to Essex, Vermont, where he killed them, the FBI said.
He then continued his travels on the East Coast, before returning to Chicago and then to Alaska.
Police confirmed his role in at least two bank robberies, saying he used the proceeds, as well as money he made as a general contractor, to finance his travels.
"Keyes buried caches throughout the United States," said the FBI, adding that it had found two such deposits in Eagle River, in Alaska, and Blake Falls Reservoir, in New York.
"The caches contained weapons and other items used to dispose of bodies.
"Keyes indicated the other caches he buried throughout the US contain weapons, money, and items used to dispose of victims."
Meanwhile, Alaska state troopers gave an update on the circumstances of Keyes' death while locked in his cell in Anchorage last Saturday night.
Investigators have "determined that Keyes used a blade from a disposable shaving razor that had been embedded into a pencil to cut himself on the left wrist," they said.
"Additionally, Keyes had used a length of bedding material from his cell to strangle himself," the statement added, noting that medical examiners were still assessing the exact cause of death.
But the statement added: "There is no indication of any criminal involvement from other persons. Pages of crumpled, blood-soaked paper that appeared to have writing on them were recovered from the cell."