Posthumous execution—executing someone for a crime even though the person is already dead—has long been a favored method of punishment. I guess it makes people feel better, if the perceived criminal died before being sufficiently punished for his crimes.

Vlad the Impaler was beheaded after being assassinated in 1476. King Richard III of England was hanged by Henry VII, even though Richard had already been killed in a battle in 1485. King Charles II of England ordered Oliver Cromwell, though dead, to be hanged, drawn, and quartered for his participation in the execution of Charles I.