Boy life just keeps messing with my time frame! Sorry this is late again!
The FBI has compiled a list of five categories of murder. They are:
Felony Murder- a homicide committed during the commission of a serious crime, such as armed robbery, hijacking or arson.
Suspected Felony Murder
Argument-motivated Murder - a homicide that occurs during a domestic dispute and is distinct from a criminal-motivated murder, the proverbial "crime of passion."
Other Motives- homicides with identifiable motives that are separate from the first three types of murder.
"Unknown" Motives - homicides with no clear motive present.
When putting together a story or book with a murder in it, decide which of these categories the murder will fall in and you can work up the characters--villain and victim--that fit the murder. To get an even better grasp of the characters it can help to write the murder scene even if it doesn't go into the story. It will help you know both characters better even if they only have bit parts in the story or if the villain has a major role in the story.
Source: The Howdunit Series: Malicious Intent; a writers guide to how murderers, robbers, rapists, and other criminals think bySean Mactire