In the US court system, you are innocent until proven guilty. I am not a lawyer, but that is our system. Even if you just follow for instance, British crimes series, you will detect right away that our US Miranda rights are specific, and VERY different from what you hear when folks are arrested in other nations. We have the right to remain silent. period.
These crimes were brutal. violent.
The person that committed these crimes is dangerous. So, unless LE was on him 24/7, there's no way they would be secure in the fact that the public in that area was safe. I would say especially because this was a college community, and the victims were college-aged students.
Also, in the US, we enjoy freedoms that allow for that freedom, until through our legal system, that it's decided that there is enough evidence for an arrest.
IMO, LE has overwhelming evidence that they have THE killer.
That flight today (with the refueling layovers) was just so long, and I wonder if BK had any utterances (about anything)? No one can say now because of the gag order.