In this quest, you're going to learn more about songs about murderers, thieves and other criminals. These songs used to be called 'murder ballads'. The term ballad, a form of traditional or folk music, means a narrative song. Within ballads, the "event song" is dedicated to narrating a particular event, and the murder ballad is a type of event song in which the event is a murder.
Perspectives are numerous. Some murder ballads tell the story from the point of view of the murderer, or attempt to portray the murderer in a somewhat sympathetic light. Other murder ballads tell the tale of the crime from the point of view of the victim.
Murder ballads make up a notable portion of traditional ballads, many of which originated in Scandinavia, England, and lowland Scotland. Some murder ballads change over time as they travel culturally: For example, "Knoxville Girl" is essentially the same ballad as "The Wexford Girl" with the setting changed from Ireland to Tennessee — while the two of them are based on "The Oxford Girl", a murder ballad set in England. Many American murder ballads are modified versions of Old World ballads with any supernatural elements removed and more focus on the slaughter of the innocent.
(adapted from source: Wikipedia - Murder ballad)