Before he committed suicide in his jail cell last year, confessed serial killer Israel Keyes confirmed some of his crimes in police interviews.
FBI agent Jeff Bell described Keyes as a "strange, calculated guy [who] in the beginning enjoyed talking about the crimes he committed."
Detectives believe Keyes murdered 11 people, but they’re still trying to determine whether there may be more who died by his hand.
"Eight other victims that we don't know where they are; their family thinks that person is missing and potentially still alive," Bell said. "We'd like to bring closure to those families."
Authorities said the unsolved cases include women near Cleburne, Glen Rose, and Lufkin — all places where Keyes was known to have been.
"Anybody who saw him anywhere in Texas, we'd be interested in talking with them," Bell said.
Driving a blue 2012 Kia Soul, federal agents said Keyes traveled through the Lone Star State in early 2012. In fact, they believe Keyes was in North Texas in mid-February last year when, Bell said, the killer went off the grid.
“He told us in interviews he made his cell phone go dead... took the battery out so he couldn't be tracked when he was out being bad," the FBI agent explained.
Around that time, investigators suspect Keyes was responsible for a house fire in Aledo and a bank robbery in Azle. Johnson County detectives are looking into the possibility he may have committed a murder there.
As investigators piece together crimes Keyes may have been involved in, law enforcement agents from the local level all the way up to the feds are seeking any new information they can get on a man they say was a very organized killer who buried stashes of money, weapons, and tools across the country to aid him in his deadly spree.
Agent Bell described Keyes as one of the "top three methodical serial killers ever" in his ability to formulate a plan of action and to remain at large for as long as he did.
Federal agents recently released several hours of Keyes' interviews in which he appeared to toy with law enforcement officers about possible murders.
The FBI has set up a tip line for any information about his crimes: 800-CALL-FBI (800-225-5324).