IMO I think it's highly likely although not confirmed that ML knew him and had some sort of relationship with him even if just on a friend level. I don't think she would just have gone to meet a stranger without having some trust build up. She was probably tired from her trip but maybe didn't want to go right home and instead agreed to meet up to hang for a bit and unwind.
Because of the reports from former roommates describing his unstable moods going from happy and seemingly easy-going to getting upset over silly things I think it was very easy for him to fake it and hold things in long enough to gain trust. In one of the articles posted here, neighbors said he was professional and friendly. Even though this was sloppy, I think he was very skilled and projecting a persona he wanted people to think of him both to feed his narcissism but also to get what he wanted namely ML and most likely others. I bet he could smoothly go from glib to solemn and depressed but spent a lot of time appearing harmless on the outside. I have no doubt this was premeditated most likely for a long time. The phone being turned off within 1 min of her getting in the car says it all. This was probably immediate and swift once she got into the car.
