A sick volleyball coach who abused several young kids — including one who was unconscious — has been found dead in his California prison, with his violent inmate being eyed for his homicide, officials said.

Robert E. Cole, 48, was found unresponsive at about 6:30 a.m. Friday in his cell at Mule Creek State Prison, where he was serving life with the possibility of parole for a string of sickening sex crimes — with at least one victim under 10 years old, the California Department of Corrections and Rehabilitation said.

Officers attempted to resuscitate the pedophile — who was arrested alongside his twin brother, Jason, a fellow coach — but he was declared dead minutes later.

Although the Amador County Coroner has yet to determine the exact cause of death, it is being investigated as a homicide, the prison department said.

Cole’s cellmate, Justin P. Welsh — who is serving 18 years for a string of convictions for violence — was placed in restricted housing while being investigated for the suspected homicide, the statement said.

Welsh, 36, was sentenced to 18 years for assault with a firearm and inflicting corporal injury, both second-strike offenses. He also received enhancements for inflicting great bodily injury involving domestic violence and has a prior felony conviction of a serious offense, officials said.

The dead pedophile was a volleyball coach with his twin brother, Jason, when they were both accused of abusing several children, KCRA reported.

Robert Cole was convicted of having sex with a child under 10, forcing a child under 14 into oral copulation with the threat of force/violence/fear and even oral copulation with an unconscious child. 

He had been in Mule Creek State Prison since 2019.