California's 'I-5 Strangler' Roger Kibbe was strangled to death, autopsy shows

He was convicted in 1991 of strangling Darcine Frackenpohl

A convicted California serial killer who was accused of strangling and raping at least seven women faced a similar fate earlier this week, with an autopsy determining he was fatally choked at a state prison.

Roger Reece Kibbe, who was known as the "I-5 Strangler" in the 1970s and '80s, was spotted unresponsive Sunday in his cell at Mule Creek State Prison southeast of Sacramento, with his 40-year-old cellmate standing nearby.

An autopsy determined the 81-year-old had been manually strangled in what authorities have classified as a homicide, the Amador County Sheriff’s Office announced Wednesday. No charges have been filed in connection with his death.

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Kibbe was a suburban Sacramento furniture maker whose brother was a law enforcement officer.

This photo provided by the California Department of Correction and Rehabilitation shows inmate Roger Reece Kibbe, 81. (CDCR via AP)

This photo provided by the California Department of Correction and Rehabilitation shows inmate Roger Reece Kibbe, 81. (CDCR via AP) ((CDCR via AP))

He was initially convicted in 1991 of strangling Darcine Frackenpohl, a 17-year-old who had run away from her home in Seattle. Her nearly nude body was found west of South Lake Tahoe below Echo Summit in September 1987.

Investigators said then that they suspected him in other similar slayings.

But it wasn't until 2009 that a San Joaquin County District Attorney’s Office investigator used new developments in evidence to connect him to six additional murders in multiple Northern California counties, with several victims found alongside Interstate 5 or other highways in 1986. Kibbe was serving multiple life terms for the slayings when he was killed.

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Vito Bertocchini, a retired San Joaquin County sheriff’s detective and district attorney’s investigator, told The Sacramento Bee he suspected Kibbe of killing others during the 10-year gap between his first and last known slayings. Investigators have said they found other women who had been killed and dumped with Kibbe's trademark of cutting his victims’ clothing in odd patterns.

He was finally captured after Sacramento police said a would-be victim escaped and they recovered a garrote made from a pair of dowels and parachute cord, along with scissors and other items.

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Investigators said they matched the cord to rope found with Frackenpohl’s body and at Kibbe's house, all with microscopic dots of red paint. DNA eventually linked him to two other victims, and he agreed to cooperate in exchange for prosecutors taking the death penalty off the table.

Kibbe never admitted to other killings beyond those with which he was charged.

The Associated Press contributed to this report.