If she did not make it home after jogging, doesn’t it seem strange that she would send an early goodnight Snap?
Perhaps someone else sent the Snapchat? Would LE be able to tell, without having Mollie's phone, if the selfie sent in the Snapchat was a pic from that day\night or one from her photo cache? Because the boyfriend might not know all the pics Mollie has stored on her phone.
I also wonder about the last text to her mom ("ok") in response to hearing what her mom was having for supper--someone else could have sent that, also.
Just because those ("ok" text and Snapchat) were sent from Mollie's phone does not mean she herself sent them.
Of course, if it turns out she really was doing homework later that same evening, my suspicions no longer apply.