For everyone who's having problems completing Case 1, i.e. You have all the evidence but can't get the second interrogation with the cycle shop owner.
When you first start the game, and go to the casino and click on the ramp, you'll get a video of the jump, and Catherine spouts off some data on the jump. YOU HAVE TO THEN GO BACK AND CLICK ON THE TIRE MARKS ON THE RAMP.
A lot of people miss this. When you click on the tire marks Catherine will note that the spring was already broken. You can't finish the game without doing this...but you can do it at any time during the game.