The police now began to investigate Barthélemy's life, and by the time the prisoner came to stand his trial at the Old Bailey were certain that the motive for the murder of Mr. Moore was robbery and nothing else. The mineral water manufacturer was in the habit of keeping a fairly large sum of money in the house, and Barthélemy had evidently brought his female companion with the object of using her as a bait to draw Mr. Moore's attention away from himself. If the merchant should become engrossed in the girl Barthélemy would be able to slip out of the room unobserved and commit the theft. This was what he intended should happen, but apparently Mr. Moore's suspicions had been unexpectedly aroused before Barthélemy could act, and in a vain effort to save himself, and also to obtain the plunder, Barthélemy had committed murder, only to find himself compelled to take a second human life. This was the official version of a tragic interview, but, as it was based entirely on conjecture, it was not universally accepted.
To say that Emanuel Barthélemy enjoyed his trial for murder at the Old Bailey is not an exaggeration. He revelled in the role of first villain in a piece which drew all London. As the hero of the duel at Egham and the subsequent trial at Kingston, he was already something of a celebrity. His achievements in France as a revolutionary were the subject of common gossip, and that they did not belie the character of the man was obvious from the attitude of studied bravado he maintained throughout the trial. He always referred to the double murder as "the affair," and while he politely expressed regret that "the affair" should have caused inconvenience to the policeman Collard, yet he could not in justice to himself, admit that there was anything in his conduct deserving of censure. He had only fired in self-defence, and no one ought to blame him for that.
The decision of the authorities to make the murder of Collard the only charge provided the defence with their one chance. Counsel for the prisoner ingeniously argued that at the worst Barthélemy had been guilty of manslaughter only. He had fired at Collard with the object of facilitating his escape. There had been no quarrel between the prisoner and his victim; they were perfect strangers, and the policeman's death was really an accident, as Barthélemy had only intended to injure him.