^^ Yup, like what @lovestar said. Kram was being possessed in mentally control by Winyoo. I think, it happened when he was in the hospital or before that. So if you watch episode 3, I think, the part where he went in to get the green stone that Prae had to wear to walk as a model. Tohroong went to stop him for stealing the stone. Kram was telling Tohroong to leave so many times before he killed her because he's trying to control himself but he couldn't, but Tohroong wouldn't leave. So he killed her. And about Kram killing himself, everyone believed and thought that he killed himself along with her, but only Prae and Sangkla doesn't because Kram shotted the security camera. So they believe that there must be someone else in the place too, however the evidence wasn't clear enough. And so because of that, it made Prae and Sangkla involved together to find out about the investigation.