Clues

  1. The prisoner was sentenced to death. 
  2. Kevin had two wives. 

Solution

Kevin was a Muslim and had two wives. Both hated him enormously. One of them poisoned her husband while serving dinner. She hoped the other wife would help in covering her tracks. Not only did the second wife refuse but knowing how much she could inherit from her dead husband, she turned the murderer in and denied any contribution to the crime. The prisoner was convicted and sentenced to death for homicide.