It's concerning they still don't know or aren't saying who they think is behind this.
I am extremely confident they know exactly who they are looking for. If they didn't they would have rough descriptions which would be getting churned out every 20 minutes by the news. The fact they dont suggests that they know exactly who is behind this but are trying not to spook them and encouraging them to resurface. They will be looking to trace this back as far as they can and keep their cards close to their chests.
Also at this stage its not really in the public interest to know whos behind it. speculation about who did it or why helps no one. Helping the families involved to grieve and move forwards will make a difference. I hope whoever is behind this is never named and remains a nobody for the rest of their lives.