About the 911 call....in my opinion...
1) Heart wrenching...I feel so badly for AM and can hear his distress.
2) I suspect the part about him saying he is "going to go back down there" is because either A) he had to go up to the house or car to get his phone or B) the phone reception was better "up" where he called.
3) I heard the "What?" by AM, but it sounded like he was speaking to the dispatcher to me. It seemed like his mind was reeling, and he missed the dispatchers last words and was asking for a repeat.
4) It is difficult to know exactly what someone might do or think when encountering such a horrific scene. I do not know whether I would think of someone possibly still being there or not. I hear fear in AM's pleas for help to "hurry."
5) AM seems sincere to me. He does not seem to be acting. To me, it sounds like he is shocked, sad, and trying to hold it together on the call. He is an attorney who has dealt with people in all sorts of situations including stressful situations. I imagine that such experiences made him try to hold it together on the call. He knows what info. the dispatcher needs and tries to remain polite and as clear as he can given the stressful nature of the moment.
6) Why does it matter that he calls PM his child? He has just seen PM's lifeless body. His first thought my be "my baby, my child." His choice of words does not seem odd to me.
7) Of course he wants to call family....this is completely normal...he has just experienced something unimaginably horrific...he must have felt so incredibly alone in that moment...
The redacted 911 call doesn't seem to shed any new light on possible perpetrators...in my opinion, it is just terribly sad.