Army Sergeant Matt Maupin, of Bartonville's 724 Transportation Company, was captured in 2004.
Friday night, an Iraqi inmate confessed to killing him.
Maupin was missing for four years until his remains were found in 2008.
Maupin is from Ohio.
His father, Keith, says he's been told the man who killed his son is in a prison in Iraq and has confessed.
Keith is traveling to the Pentagon on Monday to learn more about the confession.
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