I really wanted to answer, since I'm a *huge* Twin Peaks buff, but I'm not interested in a Steam copy at all, I don't endorse Steam and I refuse to gift Steam games to friends. Getting the game just to do another second giveaway doesn't make much sense to me, as well. Also, I already own a GOG copy. ^o^
That being said, I'm still excited to see the conversations and theories this thread will generate!
My Twin Peaks nerdiness knows no bounds which is why I love this game so damn much, I really wish though that SWERY followed his original vision and made it even more like Peaks wonder if CBS threatened to sue or something.
This isn't hard people come on! Get Steam Trading cards and stuff with it lol
Ok, then, here it goes... hahaha! Laura was killed by Leland, her father, possessed by Bob, an entity from the Black Lodge. I'm just going with the quick, easy answer. Novotnus argued it was assisted suicide, maybe because of the double life she led (drug abuse, prostitution, etc), but I don't think she wanted to die. When her father dies she forgives him, which leads me to believe she knew her death caused pain to those close to her, and therefore I don't think her death was suicide.
Then again, I haven't watched the Fire Walk With Me movie, maybe that sheds more light on the suicide theory, but based on the series alone, the straightforward answer is Leland Palmer, while possessed by Bob.