it was after fischel left the company that the money came rolling in.n to the invention deserved more than what he got, so he sued his former friend and partner, bill mclaughlin. here's the thing. it was just two weeks before the murder that the courts decided for bill. any day he was to get the $9 million he and fischel had been fighting over for years. so was it a revenge killing? sounded at least plausible. except there was something the killer left behind, something fischel didn't have access to. no, it wasn't dna, not fingerprints. something more mundane than that. >> when we got here, the door on the right was open and there was a key stuck in the lock right here. in addition to that, there was a key on a mat laying right next to the door here. >> two keys. two clues. one was a brand-new copy of the front door key. the other was a key to the community pedestrian gate, not a copy. >> those are huge because it eliminates everybody in the world from being a suspect down to only those people that have access to those two keys. >> the circle of suspect