Roger Reece Kibbe, who was serving multiple life sentences for the rape and murder of women he found on the freeways around Sacramento in the 1970 and 80s, was apparently killed in a homicide at Mule Creek State Prison on Sunday.

Not many details have been released, but Amador County Undersheriff Gary Redman tells the Sacramento Bee that Kibbe died around 12:45 a.m. Sunday, and the death is "being investigated as a homicide." Kibbe was 81 years old.

Kibbe's 40-year-old cellmate was found standing over Kibbe's body.

Kibbe was arrested and tried for the 1987 rape and murder of a 17-year-old runaway from Seattle, Darcie Frackenpohl. Frackenpohl's body was found in El Dorado County, near Lake Tahoe, not long after Kibbe was arrested on suspicion of multiple murders of women around the Sacramento area. As TruTV recounts, Kibbe's arrest came after he had already been questioned by police several times, and after one of his intended victims, 29-year-old sex worker Debra Guffie, managed to run away screaming from an assault in Kibbe's car.

Frackenpohl was Kibbe's fifth known victim, and during his trial, evidence was presented in several other unsolved murders of women connected with the killer who became known as The I-5 Strangler. Kibbe's modus operandi involved picking up women who were either in distress on the freeway late at night, or prostitutes in the area. He typically strangled them with cord that he used in his hobby of skydiving, and would cut their clothing off them in an odd pattern that became a kind of signature — something that investigators believed aroused him.

Kibbe's brother-in-law was also a Sacramento cop, and throughout his active period assaulting and killing women, he was known to pepper the brother-in-law with questions about crimes are investigated, helping him to clean up his murder scenes. He was also known to cut victims' hair in order to more easily wrap duct tape around their mouths and necks, and then remove it to prevent leaving fingerprints.

Following his 1991 conviction in Frackenpohl's murder, for which he received a sentence of 25 years to life, he would later be linked by DNA evidence in 2008 to six more killings dating back to 1977. He took a plea to avoid the death penalty, and as part of his 2009 plea bargain he agreed to cooperate with investigators to help solve other cases. He returned with investigators in 2009 to a dry creek bed in Napa County where he said he had dumped the body of Lou Ellen Burleigh in 1977. Burleigh, who left her home in Walnut Creek for a job interview and never returned, was believed to be Kibbe's first victim, however it's not known how many women he assaulted and killed in the ten years that followed, before his 1987 arrest.

He pled guilty to the murder of Burleigh, as well as the murders of Lora Heedick, Barbara Ann Scott, Stephanie Brown, Charmaine Sabrah, and Katherine Kelly Quinones, all five of whom were killed in 1986. 25-year-old Karen Finch, who was found dead in June 1987, was also one of Kibbe's victims but her case was not included in the group he was set to be tried for because unlike the others, she had been stabbed and her throat had been slashed.

Kibbe was one of multiple serial killers and rapists who terrorized the Sacramento area in the 1970s and 80s, as law enforcement discussed in the mini-series I'll Be Gone in the Dark on HBO, about the hunt for Golden State Killer Joseph James DeAngelo. Like Kibbe, DeAngelo was living in Citrus Heights at the time of his 2018 arrest.