Based on what we've seen so far, I have to say that (today) I wonder if Morgan may have continued taking the Ami without her parents' knowledge. She may have been exhibiting some of the severe side effects, however her parents didn't realize it. Dry mouth (always had a water bottle), loss of appetite/nausea/chills/sore throat, delusions, new or worsening agitation, anxiety coupled with periodic exaggerated feelings of well being, hallucinations, etc. eventually leading to suicidal thoughts and actions.
I believe that Toni and Steve believe she was stalked and murdered. I truly do. As for the wildlife camera pic that keeps hanging me up, I think maybe it was just a nosy neighbor skulking about wondering what all the police activity was all about. When he realized that he was photographed, he tried to knock the camera down.
I need to go back and research the man seen on the front porch. I thought he had been heard entering numbers into the keypad by Toni, but someone posted that Morgan reported hearing this when she was home alone, so perhaps I'm remembering wrong and Toni simply saw someone on the front porch. Off to check the blog.
If/when Toni shares more pics and video of the stalker, and the first ME report, I might change my mind on this. But as of this moment, this is the simplest explanation I can come up with.