These are my thoughts as well.
I don't feel AM is going to have any involvement with the deaths, too obvious even for this powerfully connected family. Wasn't there a hearing scheduled or held a few days prior to June 7th when Maggie & Paul were killed? I read that somewhere but don't remember where, so take that as unconfirmed.
Someone may have been convinced justice would never be served and decided to take it into their own hands, JMO. Add- Paul was not a party to the civil case filed by the Beach family. So killing him would not effect the case, it only closes the criminal filing. Maggie would be killed because she could identify the shooter(s).