At a press conference DS mother emphasized the "recognizability" of her vehicle, all the mud! That in mind, I would be surprised if someone didn't recognize her exiting telegraph road, mainly ANY colleague. She is defined as bubbly, seemingly knows lots of people and has worked there for a long time. And it explains why they seem pretty sure she indeed left the lot at 5PM as opposed to being held hostage in the lot. Good chance someone leaving at the same time saw her out on telegraph road in that unforgettable car.
Here's where it gets interesting. Someone who recognizes her, stands a good chance of noticing a potential POI (i.e. SG) in the car. Good chance the SG is one of the most widely recognized employees. And if he saw someone recognize him (perhaps honk, wave on a Friday afternoon when everyone's excited to be getting home) he would be the most concern about an alibi, or changing the "last place seen" to somewhere else. This is a good reason to explain why he could have driven the car home.
The cat may hold the clue to why it is suspected she never entered the apartment. An underfed cat. An empty dish. Or a packed overnight bag which she forgot to take to work that morning.
But regarding the published texts. The photo of her phone. Well actually if you analyze it, it doesn't necessarily support anything in terms of who is sleeping at whose house... HOWEVER, I am concerned about the words the friend chose "are you alive..lol" or "are you dead..lol" (I forgot exactly how she wrote it). The reason I am concerned is what if DS said she had a stop, or conversation that had to be done prior to coming over. The friend (who could know who she had to meet for those minutes)knows DS doesn't like or is possibly afraid of that person. Ergo "ARE YOU STILL ALIVE...LOL"