I am to the point where I have to make a fake fingerprint but when I go to get the knob out of the evidence bag it won't come out. Any help out there? Thanks.

The knob is not in the evidence bag.
It is in one of those frames in inventory.
Those things at evidence bag are only for info.

Thanks. Now I am at the end of the game and my cursor decides to be jumpy and I keep getting electrocuted. Any help? Thanks.

It might be best to post at Glitches forum to see what they say.