I don't think LE was hindered much not having SM's actual phone because they had both her iCloud backup, a record of phone and data usage from her mobile carrier Verizon, and the forensic analysis of the Morphew wifi activity which was very extensive given the lack of phone signal in Maysville.
I recall LE discovered the spy pen very quickly under search warrant after SO tipped them off that she purchased the device for SM. Although investigators had knowledge via the pen recording that SM was communicating with an unknown male, it wasn't until November that they were able to identify JL when they discovered SM's LinkedIn. I recall investigators identified JL via LinkedIn.
JL was probably the source for what apps SM/JL used to communicate with each other including when SM first reached out to him and the brief period they stopped communicating after JL's daughter discovered text messages from SM on her dad's phone.
As for what happened on 5/9, we know that SM was sunbathing outside. We know that she communicated with BM via text and offered to meet him but he told her that he was on his way home. Whether or not BM actually ate veggie stew for lunch with SM or instead crawled around outside disabling the game cameras, looking for the alleged dead turkey, we know that SM was aware that BM left PP again because she communicated to JL that she was "alone again." We know that BM changed the blade on the bobcat and called/texted SM nine times before returning to PP the second time.
I think BM arrived home in a fit because his calls to SM went unanswered. Seeing her vehicle still at home, I think BM moved rapidly around the house looking for SM. I agree the million-dollar question is where was SM when BM returned home from DSi!
I think SM had probably finished sunbathing and went to her closet to undress and perhaps wait for JL to connect with her on Whatsapp. Or she could have taken a shower. Whatever she was doing, I think she'd locked BM out of the bedroom and he broke it down to get to her.
I never bought the idea that BM used his 22 shotgun as a tranq gun when he could easily overpower petite SM and inject her with the tranq dart. However, I wouldn't put it past BM to either threaten suicide or SM in the bedroom with the 22. I think he told SM marriage was for life and they were both going to die that day. And when SM didn't respond to his threats, BM made certain that SM was the one that would be dead. MOO