The next morning, Holmes has coffee, yogurt and fruit for Watson, who is still in bed. They're going to the Property Clerk's Office, because that's where they keep Exhibit C. It's just a handwritten note with the names of the criminals next to their coffee orders, but the jury looked at it three times. At the trial, it was just proof that the criminals knew each other.
Holmes shows Watson the paper. Here are their orders: Justin, Grand 2 Sugars; Alex, Cai soy latte; Jeremy, Coffee soy; Amelie, Van. soy latte. I'm going to come back to this order in a few paragraphs, so I want you to notice the names. Justin, Alex, Jeremy, and Amelie. Watson notices that there are three soy drinks, which is kind of a high ratio. But Holmes is more interested in some gibberish on the back of the paper. It's Malboge, which is a computer language that's supposed to be impenetrable. But Holmes has a contact who knows it. His theory is that someone from the jury recognized it as computer code and figured out how to use it to break the safe's encryption. And on looking through the jury records, he settles on Justin Guthrie, who was a former software engineer.
Holmes's phone beeps as they're on their way to see Jason Guthrie. The Malbolge code was, in fact, a random number algorithm. It took ten-digit strings from pi, which look random but are predictable. Holmes is now confident that Guthrie recognized the code. But there's a policeman at the door to Guthrie's building, because it's an active crime scene. It seems Mr. Guthrie jumped out the window of his apartment!
Holmes is playing Guthrie's piano when Gregson and Bell arrive. Holmes says it wasn't a suicide. He points them to some blood on the wainscoting, which he and Watson found. I really like that he gives Watson some of the credit for that. The blood spatter suggests that someone was hit in the nose. Holmes leads them to some vases filled with decorative stones. But one of them is missing a layer, and many of the stolen diamonds were uncut. So the co-conspirator stole them. And he was in a hurry, so here's one he missed. Gregson is sold: get some more detectives down here! Holmes is dazzled by his own cleverness and wants to duck out of Watson's dinner now that it's a murder investigation.