Murder is a legal term for when someone unlawfully kills another person. In order for a killing to be considered murder it must meet certain legal requirements such as malice aforethought and that the person must have intended to kill rather than merely cause grievous bodily harm. Murder is generally considered to be more serious than manslaughter.
Most murders are not reported to the police but some murder cases will be newsworthy enough to generate local, national or even international media coverage. As a result, the murder will receive an inquest or trial and if convicted it will be reported on in books, TV shows and films.
Some victims of murder will be well known, or have a connection with a famous figure and this may warrant the creation of a separate article on them (without the murder) for purposes of encyclopedian notability. This is especially the case if other factors contributed to the death of the victim that could be considered as breaking the chain of causation, such as suicide.
The backstory of the murderer is also important as it gives the reader a better understanding of why this character became so violent and how they ended up murdering their victim. This can include things like genetics, environmental exposures in the womb, illness or malnutrition as a child, damaging substance use later in life and emotional trauma during childhood that causes physical changes to the brain. It can also be about a psychiatric condition such as schizophrenia or post-traumatic stress disorder that can lead to violence.