I think the Dateline show suggests the type of conversation that took place, so here's my guess:
We learn from the show that Travis had already been to the bishop to "set his life back on the right track." I suspect that he was counseled/warned but no action had been taken, meaning he had not been disfellowshipped or excommunicated. Now he has failed again to control himself because his succubus showed up. He is very disappointed in himself. You can see the disappointment and sadness in his face in the shower. This is not a man who is cheerfully posing for sexplay photos or even "one last time tastefully to remember you by" muscle shots. I am guessing he is running out of patience because he has repeatedly asked her to leave before his roommates get home...reminding her yet again that she is just his dirty little secret.
She asks for a couple of sitting shots and promises to be on her way. She take a couple of shots without the flash, crouching beside him. They are talking. He tells her he has been to the bishop after she left. He promised the bishop he would stay away from her. He tells her that the next level of discipline would be for the church to take action against his membership and he is unwilling to lose the thing that means the most to him in the world for her... and he gets stern. She is dressed, removed her luggage, and here she is back again when he specifically asked her to LEAVE. He tells her she has no respect for the wishes of others. He has violated his privacy again and again, he knows she is stalking him, slashed his tires, and he has never reported it to the police or the bishop, but now he is drawing the line. He tells her that if she contacts him again, he will report to the police the money she stole from his bank account. Get the hell out, he says, and I never want to see you again. She stands and (closes the door or not) and takes a last picture with the camera at waist level. He has a wtf look of fear on his face because that's when he first sees the gun in her right hand. FLASH! She shoots him right in the face.
(two weeks ago a WS poster magnified his pupil and posted a photo which clearly shows her standing silhouette and the camera flash very clear at waist level, the camera being unmistakably in her right hand on the right side of her body... leaving her left hand to hold the gun. )
because she has only seen gunshots in movies, she is unprepared for him to react by lunging at her, screaming. He's lunging at the gun, not the camera. The camera shoots the ceiling because he's coming at her and she's taken by surprise, perhaps he is even coming in low like she demonstrated. He's supposed to collapse, dead on the spot and she's horrified. He's on the ground writing and screaming now, she tries to shoot him again, gun jams, she runs to get the knife. She comes back and he is at the sink saying "Call the neighbors." He doesn't realize even yet that he was shot on purpose. He is looking in the mirror but blood is in his eyes. He splashes water on his face.
She attacks him stabbing and we know the rest.
