Published: Jul 22, 2013 12:11 PM EDT

LARGO, Fla. (AP) - A man already facing a second-degree murder charge for killing his girlfriend last year is now accused of stuffing wet toilet paper down the throat of his cell mate at the Pinellas County Jail early Sunday and then strangling him.
    
Scott Alexander Greenberg, 28, of St. Petersburg apparently told fellow inmates he'd rather be executed on death row than spend the rest of his life in prison, according to Pinellas County Sheriff Bob Gualtieri. He added that said an inmate hasn't been killed by another inmate at the jail in the 31 years he's worked for the agency.
    
The Tampa Bay Times (http://bit.ly/14uTDcu ) reports that Greenberg and Kelly Damon Harding were placed in a cell together late Saturday after both were put in protective custody due to aggressive behavior at the jail. Lights went out at 11 p.m. and deputies checked the cell at 12:52 and found nothing unusual.
    
According to a sheriff's office report, a short time later, gurgling and thumping sounds were heard and Greenberg said, "I did it, it's done." An inmate in a nearby cell asked what he had done. "What I'm in here for," Greenberg replied.
    
At 12:58 a.m., Greenberg yelled to deputies that a man was down. Deputies found Harding unconscious. He was taken to a hospital where he died.
    
Gualtieri said Greenberg broke bones in Harding's neck and asphyxiated him with a small amount of toilet paper in the cell.
    
Harding was serving jail time for a trespassing conviction that was pleaded down from a burglary charge. Greenberg is accused in the death of girlfriend Jennifer Zale, 26, during what he maintained was a consensual sexual encounter that got out of hand at a local hotel.
    
The sheriff said the injuries to both victims were similar.
    
"What's clear is that he had a plan, and he decided to execute that plan," Gualtieri said.
    
Records show Harding had used racial slurs, spit at inmates and defecated in the recreation yard and Greenberg had thrown a punch at staffers and fought with inmates. Greenberg fell in the shower and hit his head. He was sent to the jail's clinic and then allowed to select a cell to spend the night.
    
It was about 10 p.m. when he joined Harding, whom he had never met.
    
Greenberg is now charged with first-degree murder in Harding's death.
    
According to the Department of Corrections, Greenberg's past convictions include drug possession, interference in the custody of a minor, check fraud and domestic battery.
    
Harding had served prison time at least six times since 1985 for charges including burglary, cocaine possession and carrying a concealed firearm.
    
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Information from: Tampa Bay Times (St. Petersburg, Fla.), http://www.tampabay.com.

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