California's infamous "I-5 Strangler" Roger Kibbe has been found dead inside his cell at Mule Creek State Prison.

At approximately 12:40 a.m. on Sunday, a MCSP correctional officer was conducting institution population counts when they observed inmate Jason Budrow, 40, standing in his cell with Kibbe lying unresponsive on the floor.

"Medical staff immediately responded to the incident and transported Kibbe to the institution health care facility for higher level of care," the California Department of Corrections and Rehabilitation said in a news release Monday. "Life-saving measures were unsuccessful and Kibbe was pronounced deceased at 1:23 a.m. by institution medical staff."

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Kibbe, 81, was serving multiple life sentences without the possibility of parole for seven murders between 1977 and 1987.

He was first sentenced to 25 years-to-life in May 1991 for the murder of 17-year old Darcie Frackenpohl, a runaway from Seattle whose body was found at Echo Summit in El Dorado County.

He later plead guilty in 2009 after DNA evidence connected Kibbe to six more killings dating back to 1977.

Roger Kibbe (Photo courtesy of California Department of Corrections and Rehabilitation)

MCSP’s Investigative Services Unit is investigating Bibbe's death as a homicide and the Office of the Inspector General has been notified.

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Budrow, 40, was sentenced on June 29, 2011 from Riverside County to serve a life without the possibility of parole for first-degree murder as a second-striker.

He has been rehoused in the prison's administrative segregation unit pending the results of the investigation.

(Photo courtesy of California Department of Corrections and Rehabilitation)

MCSP, opened in 1987, houses 3,864 inmates and employs approximately 1,700 people. The prison provides several vocational, academic, self-help, volunteer, and other rehabilitative programs.