“Or perhaps the suicide,” I said. As one, Baker and Carpenter gave me a look. “Hear me out,” I said hurriedly, and before they could interject, I continued. “Abbot McKenzie had no great love for Dalton Heath. Marchand leaves McKenzie for Heath, then won’t give McKenzie a second chance when it turns out Heath wasn’t such a good choice, either. Heath presents himself as the senior partner in a partnership that wouldn’t exist without McKenzie’s knowledge and expertise, and then we catch him embezzling from that partnership with little motive. There are two possibilities: Heath was indeed embezzling, and he was discovered, or McKenzie—the director of finance, recall—might have been framing him. Heath discovers the oddity in his accounts, panics, and attempts to move the money back quietly, without raising the question of how it came into his possession in the first place. I discard the former possibility. Heath is worth nearly one million marks; it’s suspected he embezzled fifty thousand. Without some evidence that he wanted for an amount so trifling to him, and in light of McKenzie’s many reasons to harbor a dislike for Heath, I consider it more likely that McKenzie was indeed attempting to set up Heath to take a fall. The question then becomes, what follows from that assumption?

“Let us consider Dalton Heath, and how he might have behaved were he at the scene of the crime that night. If he had come with the purpose of killing McKenzie, he would have had a plan. We would never have caught him on tape fleeing the building, nor would have he tossed the murder weapon out the window. He might have gone to the apartment to confront McKenzie, but how would he have known to look there rather than at McKenzie’s own apartment? If it were McKenzie embezzling in Heath’s name, might not it be the case that Heath knew nothing about it? That he would not have had any motive to be at his company’s apartment the night McKenzie died?

“If Heath wasn’t present, what are we left with? A random killing? It seems unlikelier even than usual in a building with security in a well-off neighborhood in a well-off district. We are led back to McKenzie. A close friend of his remarks that he is a great talent at nursing grudges, and he certainly has cause for one here. He frames his foe for theft on a large scale, but it isn’t nearly enough. The woman he loves is gone, out of reach, and any time he thinks proudly of his work, he must also think of the man to whom he owes his success, a man who has taken all the credit while contributing nothing of the scientific knowledge required in their line of business, the man who has been doing so since the beginning and cuckolding him along the way. McKenzie ignores the success the partnership has seen, and discounts out of hand any suggestion of benign intent on Heath’s part—filtered as McKenzie’s perceptions were by two years of cold hatred, how could he not regard almost every one of Heath’s actions as a calculated insult? Finally, he reaches the breaking point. He says to himself, ‘I may die, but I will die with the knowledge that Dalton Heath will be called thief and murderer to the end of his days.'”