Denver » Human remains found in Colorado may be related to a serial killing investigation, authorities say.

"There were remains found in Eagle County yesterday," FBI spokeswoman Kathy Wright said Tuesday in Denver. The FBI is assisting in a multi-state investigation of murders that may have been committed by Scott Lee Kimball, 42, who has not yet been charged with any murders but is serving a 48-year sentence as a habitual criminal.

A source close to the investigation who asked not to be identified because they were not authorized to provide details said the remains are believed to be those of Terry Kimball, 60, Scott Kimball's uncle. They were found in a remote area of Vail Pass, according to the source.

Authorities believe Kimball is responsible for the disappearances of Terry Kimball and three women. He has provided information to investigators about where the bodies might be found.

The remains of Leann Emry were found March 11 in the Book Cliffs of Grand County, Utah.

Emry, Kaysi McLeod, Jennifer Marcum and Terry Kimball were all last seen with Scott Kimball in 2003 and 2004. McLeod's remains were recovered in a remote area of Jackson County in June 2008. The remains of Marcum have not been found.

Wright said the remains were discovered with the help of local and federal officers.

"We have no direct information on who is responsible for the death of Terry Kimball," she said.

Wright said a coroner will have to confirm whether the remains that were discovered were those of Terry Kimball.

Terry Kimball disappeared in late 2004, shortly after he arrived in town and began to stay with Scott Kimball.

Scott Kimball told people that his uncle won the Ohio state lottery, then went to Mexico with a woman.

Grand County, Utah, Sheriff Jim Nyland said he is waiting for Kimball or the FBI to produce a more exact searching location before looking for Marcum's remains again.

"Every place that he told us that could be a location, we went out there and searched and just came up with nothing," Nyland said.

Tribune reporter Nate Carlisle contributed to this report.