It is unlikely that Gannon and Friday would have read Miranda Rights to any of the suspects and then question them without their parents being present, due to the fact that they were minors.
When Friday and Gannon are interviewing Mr Enquist they pass a 125 pound safe very obviously sitting wide open on a table. Mr Enquist says; "Oh, brother. Right here and I didn't even miss it!" He obviously meant to say "I didn't even see it!"