4C

Any thoughts on finding the three murder victims all went to the same school?

Possibly something happened at the school when they were younger and that’s why they were murdered.

This connection is no co-incidence. Knowing if they were friends at school may provide useful clues.

That is the connection that has been missing and it goes back to their youth

I agree with all above.
And could the scarring on the arms refer to some sort of schoolboy ritual - a ‘friends forever/blood brothers’ type of thing?