I think regardless of who did it or their motivation I think we can assume now nearly 10 days in that it was orchestrated with a degree of capability.
I know one of the parents said that they created a mess and lots of evidence. That doesn’t necessarily translate to reckless and poorly executed.
After 10 days and with no arrests or even suspects it suggests there is no incriminating phone pings, no clear cut cctv or video evidence of them entering or leaving the scene in a highly populated urban area. Probably no definitive finger prints or dna to easily match the perpetrator (Perhaps suggests no previous record to), and with 500 tips not yet eliciting a suspect their post murder behaviour has also probably been controlled - I.e no breaking down and confessing, or the other end of the scale - boasting. Which considering the horrific murder of 4 people maybe suggests a certain type of personality.
The individual has either got very lucky or planned extensively to avoid the usual digital and physical mistakes that lead to quick identification and apprehension. And you feel after 10 days if any of those mistakes had been obvious we would probably already have seen the result.
Not sure we can conclude anything definitive but it’s another sign to me that this wasn’t spur of the moment, or even quickly planned after something that had happened earlier in the evening or within the last few days. I’m sure behavioural analysts would also suggest it’s someone who is thinking about the process and not just purely acting out of rage.