FOLSOM, Calif. (AP) — Officials say a state inmate is suspected of killing his cellmate at Folsom Prison.

California State Prison, Sacramento, correctional Lt. LeVance Quinn said Tuesday that a guard spotted 32-year-old Sergio J. Castaneda III lying unresponsive on his cell floor late Monday.

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Investigators at the high-security prison east of Sacramento named his cellmate, 47-year-old Arthur Lane, as a suspect.

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Lane is serving a life sentence for a Sacramento County murder plus a four-year sentence from Kern County for assaulting another prisoner with a deadly weapon.

Castaneda was serving a three-year sentence for a Los Angeles County robbery. He had another four-year sentence from Monterey County for battery on a non-prisoner. He previously served a two-year Riverside County sentence for injury to an elder causing death or great bodily injury.

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