Really?Why are you assuming he has been interrogated? They woke him up at around 3 am, told him to get dressed, put him in handcuffs and took him to be booked. I think he was well aware why LE was there and he's well aware of his rights.
Why would he be interrogated? One of the hard parts about cases like this is that it's possible for a murderer to go all the way to Death Row or life in prison and never give an account of what they did or why they did it. Joe DeAngelo (GSK/EARONS) comes to mind.
Wow!
I thought interrogation, presenting alibi, etc. is an integral part of investigation.
With a lawyer present.
Phew!