Haha all right this is how you get it.
Go to heavyrainps3.com. Register your email address there where it says "Join the hunt for the Origami Killer, Experience Four Days Now". Then go to
http://www.precinct52.com/case1117_briefing and enter your email and password there. It'll say you need to collect 4 pieces of evidence to present to the FBI or something like that. Once it takes you to the screen with the evidence choose these 4: the origami bird, the short cigarette butt, the tire tracks that say "Import?", and the coffee shop that says Diner and has a picture of an Egyptian pharaoh. It'll say congratulations and give you a promo code to download the demo.
Now it might take a while to get those sites to work cuz apparently the answers leaked online and too many people were on that site. So if it doesn't work try again later. Hope it works out for you.