I think the killer in the first question in the restaurant is the lady or the man in the red shirt, i think the lady because the body is in the ladies room, but the man in the red could have sneaked in and got out of the rest room faster as he is the one closer to the door and could be blending in with the people around him.
The scene with the lady on the gound, I would suggest to be a suicide though he could have been posed by the killer but based on the blood from hee head she was not shot from behind and i don't know where the door is, she was clearly looking at the mirror so she could have seen the killer and someone fight back, but there is no sign of struggle and no proof of anyone breaking in, wait, hold that thought! I think she was in front of a window! And I actually think she was murdered, she was not posed correctly after she had died! The chair did not and should not have fallen to the side, it would have fallen backwards! And her body would be up against the wall not on the group in almost the fetal position! My final conclusion is that she was MURDERED