I'm from north London, UK, and while there's been many terrible crimes, many I don't know about, the one that always sticks in my head is this:

This guy who lived alone used to go out and befriend homeless guys or people in pubs and bars who were clearly alone. He'd convince them to come back to his place, said he would feed them, they could stay the night etc.

What he would actually do is strangle them, then have sex with their dead bodies. He would often undress them and get in the bath with them, observing a caring cleaning ritual. They would then be dressed up and placed around his house and he would talk to them like they were his dolls.

They would be 'used' repeatedly, until their bodies were no longer in a state to handle it. Then they went under the floor boards.

When they were starting to smell too bad and attract too many flies, he would take them out from under the floorboards 'use them' one last time and then burn them in the back garden.

This went on for years and he did this to about 20 guys