Instead of a murder being reported over the scanner a fire is reported. when arriving on scene you will find an apartment or a shop burnt. This could be shown by adding blackened decals onto the walls, and perhaps even a charred body.
The clues given would of course be CCTV, witnesses, perhaps lighters and ciggarettes with finger prints.
If the arsonist isnt caught they will strike again.
The arsonist themselves could also be motivated by revenge on a neighbour or a boss at work. meaning the address book would come into play. It could also be an insurance job by a boss on their own work place.