Marvin Wilson, 54, whose IQ was tested at 61 several years ago, was executed at the state prison in Huntsville for the 1992 shooting death of 21-year-old police informant Jerry Williams in Beaumont, KWTX-TV, Waco, reported.
His execution by lethal injection took place after the U.S. Supreme Court rejected his final appeal.
While Wilson's IQ was well below the 70 generally regarded as the minimum for competency, the state's attorneys argued the single test was fault and that other psychological testing showed him to not be mentally impaired.
A co-defendant, Andrew Lewis, 46, received a life prison sentence.
Notable deaths of 2014 [PHOTOS]