Prison guards make sure to keep their jails free of items that could be used as makeshift weapons, but what do you do when you have an inmate who is already in custody for allegedly killing his girlfriend with toilet paper? Do you treat toilet paper as contraband?

Apparently the Pinellas County Jail didn't take that precaution, and now Scott Alexander Greenberg, 28, is accused of killing his cellmate with toilet paper.

Early Sunday morning, 48-year-old Kelly Harding was found unconscious in his cell. He was transported to a hospital and pronounced dead. Authorities found wet toilet paper stuffed down his throat and determined he had been strangled.

Suspicion fell on his cellmate, Greenberg -- perhaps because he's awaiting trial for a similar death.

In 2012, Greenberg strangled his girlfriend, Jennifer Zale, to death. During sex, Greenberg stuffed toilet paper down Zale's throat and choked her. He claimed the death was accidental and that the two were engaged in a consensual game of sexual asphyxiation. After she lost consciousness, Greenberg waited eight hours to call 911. He was originally charged with manslaughter, but prosecutors bumped his charges up to second-degree murder.

Greenberg now faces first-degree murder charges for Harding's death and remains in jail in an isolated holding cell.

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