So I am going to try solve the murder mystery
So as first the killers have patterns the people which are solving the case should look patterns they say a lot of about the killer. As second to collect and gather as much evidence as possible, also to try to see what type of people is he searching... their behavior... their social status, their life... and so on and so on. As third to try to make a trap for him, most times killers just get in the trap if they are clever enough.
As Fourth to try to search as more behavior patterns of him as possible... sometimes the killings speaks volumes, it's called art. Killing is like the music, stories it's an example of art. He is going to speak soon, who knows, but I am sure soon he is going to have spread a message. What he is doing is for reason, killers are man reasonable men.
His killing could have some kind of message, that he does or that or that probably there is reason, did he faced the victims... when he was killing them.
By which way he was killing them... while they are alive and he removes little by little parts from their skin or while they were dead?
How much time is between his killings? How much times does he spend with each victim... is there a victim with which spends more time and with other less?