Medieval Illuminated Manuscripts website has an interesting collection of medieval illustrations, including this set showing deaths by unnatural causes:
Methods of murder and torture... It is tempting to think of medieval society as a violent society. Many hundreds of the pictures from the collection of the Koninklijke Bibliotheek and Museum Meermanno seem to confirm this. They show a rich variety of people being tortured and killed. Thanks to the method of description, various types of violent acts can even be separately retrieved from the database, as is shown below.
The killing of the prophet Isaiah is from Speculum Humanae Salvationis.