did he or didn't he?

yes of course he did it when kirsten found that he kill the dog she wanted to kill him and we didn t saw what happens but that is the mistery of the movie
so he did it her friend deborah help him and he use the old man to kill deborah because she told him that she will talk

so he is the killer he is very damage in the brain because he saw his mother jumped in the window and he saw everything and the fall down too

[deleted]

I assumed that he did kill katie and was indeed talking about her when he told his father that "he missed her so much." Right before that scene it shows a flashback of Katie in the country where they had their food store; HAPPY.

David said at the beginning of the film that he wanted to run a food store.
Katie seemed to be happy with this decision. She even said she didn't care about all the stuff that they received after David began to work for his father.
David didn't show any of these problems until after his father put him on edge. Which is probably the same thing his father use to do to his mother before she killed herself. So Davids Fathers behavior probably brought back some unhappy memories causing him to Snap after all those years.

I assume that he said he missed her so much because, as the flashback shows, katie was happy where she was in the country. He even called katie PERFECT at the begining of the movie because there was nothing he could do that she didnt love. So when she started to not love the things he was doing and the person he was becoming, he couldnt take that the "perfect image" was shattered. And David DID love her it's just that after all the pressure from his father, katie couldnt handle his mood swings, and they "drifted." so their relationship became strained until he SNAPPED. When he says HE MISSES HER i assume he's saying he misses what they use to have and what could have been, and even to a very small degree who he was himself before he turned into this uncontrollable monster.

I always felt he did it all. I think a lot of other people did too. I cant' believe a jury in Texas let this guy off, even after the knew he chopped the neighbors body up and dumped it. Come on!!!

Also why would he have drove Katie's car to his fathers house and left it there, only to have the father look in the trunk. Why would he do something like that, unless he thought she was in there as well. He knew it was strange for him to be there alone in her car, and then leave it and walk off. The dad knew, and that is why the movie presumed that he might have killed his father in the end. The last loose end.

I'm a voodoo child baby
I don't take no for no for an answer.....J.H.

I think it depends on what story you're talking about.
Movie: I don't feel they left it open at all. Obviously it shows how he could have killed her and got away with it.

Real life Story: In my opinion I think he killed her but you could never prove it. These people have so much money. When you live in a family like that you can literally 'get away with murder'. They will do, and other people will do, anything for you including covering up a murder because of who you are. Then the things he says just tells me this guy is a sociopath. In an interview he says he 'cried' during scenes of this movie. Then he says if anything did happen to Kathie he 'had a large chunk to do with it'. This man is sick.

I think the movie made it clear that he (Marks) did kill Katie. I also think he was truthful when he told his dad he "missed her". I think it is possible to love someone (in some form) and still be able to kill them yet miss them when they're dead. Human beings can be very complicated and "messy".

As for the Durst case that this movie is loosely based on, I fully believe he killed his wife based on what I've heard and read about the case. Not long after his wife was determined to be missing, Durst was seen throwing all her clothes and belongings away. He didn't donate them; he simply threw them away like so much trash. He also gave very little help in the search for her and the police's investigation into her disappearance.

I also have suspicions about his involvement in the death of his female friend who was supposedly his best friend who would do anything for him. She'd spoken briefly to some detectives and was going to be questioned further about Durst's wife's disappearance shortly before her murder. Coincidences happen, but the timing of her murder just smells fishy.

I also have doubts about Durst killing his neighbor in Texas in "self-defense". Durst is a completely unreliable person. Regardless, he has to be one sick puppy to dismember the body and dispose of it without reporting anything to the police. Innocent people do not chop up bodies.

We're playing house.
The boy is all tied up.
Roman Polanski's house.

That doesn't matter. The film is based on facts and the facts are inconclusive.

I actually thought the movie took a pretty strong stance on the side of him being guilty.