I'm not quite caught up yet, but something just occurred to me.
Is this a possibility?:
The killer goes and does the job, and leaves, starts walking, has a burner phone.. he has it set up to connect to whichever wifi network becomes available, he's looking at it and checking it while he's walking at a good pace. A few houses down from the Shermans, the people weren't knowledgeable enough to set their modem/router settings to prevent uninvited strangers from utilizing their wifi network.. the murderer sees he can now connect to someone's wifi, so he connects, and then dials 911.. and hangs up. He immediately removes the battery from the burner, or turns it off, or crushes it with his boot, whatever (or did he first call a cab to meet him a few blocks away, to take him to the airport?). LE receives a hangup 911 call, tries calling back, they get nothing, this burner phone had no voicemail capability, or it was not yet 'set up', etc. So they keep looking into it, and appear the next morning to the nearest address LE can determine the call came from, to ask the homeowners if anyone there called 911. The purpose of the killer calling 911 in the first place, may have been as 'window21' has indicated.. perhaps the hiring party had given that instruction, so that the bodies were found immediately? Or.. not? Because how would the bodies have been found, if LE wouldn't be able to determine from which address the call came? But wait. The purpose of the 911 call was not for LE to find the bodies, it was to make LE think that Honey had called 911 because she was being murdered by her husband!? Thoughts?
Edit to add.... in my theory above, this phone did not have any 'service', it worked solely with 'wifi'.. no wifi connection, no ability to use the phone. The perp would've had to use an app to be able to use it to make a phone call, which would've been via wifi.