Prosecutors say he killed the men to cover up a series of robberies throughout the Triangle. The jury also found Cooper guilty of robbery.
Cooper's lawyers didn't dispute that he was behind the murders in 2006 and 2007.
But, defense attorneys argued that years of physical and emotional abuse by Cooper's father left him with diminished mental capacity and unable to plan the killings.
Prosecutors described Cooper as a cold-blooded serial robber who killed people to prevent them from identifying him.
The trial now enters the sentencing phase. Cooper could be put to death.
The judge dismissed the jury and told them to return Wednesday to begin hearing arguments from the prosecution and defense on Cooper's sentence.