A lot of things contribute to the investigation of a crime - the intelligence of the killer (does he leave clues?), the perseverance of the police, presence of witnesses, technology available, and cooperation of the victims. If one of these works against the search for justice, the investigation can slow down, or worse, justice is not served.
There was the Witch, who took children and made potions and medicines out of their blood and flesh. Have you heard of Snowtown, a town in Australia where the 'Bodies in the Barrels' were found?
There was also Kenneth, the man, who, after being given second and third chances, chose to ruin his and other people's lives through murder. Interestingly, his case was similar to Austria's Jack Unterweger, the prisoner, turned celebrity, turned serial killer, who killed not just in his home country, but also in the United States.
Lastly, you'll meet Lorenzo - the killer in the neighborhood.
In all these cases, you will discover how the above mentioned factors will contribute to the development of the investigation.....