“Very good, Sergeant,” Savidge said. “Earlier, his lordship suggested that members of the jury might appreciate an explanation of the term fingerprint. I should much appreciate it if you would be so good as to explain this science.”

Sergeant Collins managed the explanation with skill and aplomb, explaining that the ridged lines that appeared in loops and whorls on the tips of the fingers, while they might be classified in a limited number of general patterns, were absolutely unique to each finger and, more importantly, to each individual, man, woman, and child. All people’s fingertips carried a coating of perspiration and oils. When the fingers came into contact with any relatively smooth surface, they left a print of the fingertip ridges, much like that of an inked rubber stamp. When the surface was dusted lightly with a powder, the prints became visible. These could be photographed and the photograph enlarged for easier study. Charles noticed that as Sergeant Collins spoke, the jurors and spectators were holding up their hands, inspecting the tips of their fingers and whispering to one another.

The sergeant continued his explanation. Some fourteen years previously, Sir Francis Galton had developed a system for classifying and identifying fingerprints; the system had been recently improved upon by the Assistant Commissioner of London Police, Edward Henry, and was now in place. Many convicted prisoners had been fingerprinted; every suspect was fingerprinted upon his arrest; and the prints kept on file for possible future use.

Savidge nodded. “Thank you, Sergeant. That was enlightening. However, you have not mentioned the use of fingerprints in a court of law.” He paused. “It is true, is it not, that fingerprint identification was recently validated-only two days ago, in fact, and in this very courtroom. Is that not the case?”

Collins nodded, speaking now with an eager pride. “Yes, indeed it is, sir. I am glad to say that Henry Jackson was convicted of burglary on the strength of his left thumb. Put it into paint that was not quite dry on the windowsill of a house he was trying to burgle.” He grinned, straightening his shoulders. “I checked the print in the paint against Mr. Jackson’s left thumb, which was taken when he was having a bit of a rest in Newgate last year, and it matched. Got seven years, he did, and deserved it, too.” The spectators, enjoying Sergeant Collins’s pleasure in the conviction of Mr. Jackson, broke into scattered applause.

Savidge chuckled. “Congratulations, Sergeant. You are to be commended for your careful investigation. Without your expertise, a dangerous thief might still be roaming the streets. Clearly, fingerprints deserve special attention in every police investigation.” He paused for a moment to let the jury consider this, then went on. “Now, Sergeant, with regard to the defendants in this case. I have entered their fingerprint records as Exhibits E1, 2, and 3. You are familiar with these records?”

Collins became serious again. “Yes, sir. The prints were taken at Holloway Prison, sir.”

“And you have examined the ginger-beer bottles entered as Exhibit B.”

“I have.”

“Since these bottles were discovered in the defendants’ rooms, one would quite naturally expect that the defendants had handled them and left their fingerprints. Is that not the case?”

“It is, yes.”

“Then tell us what you found, Sergeant. Did all three of the bottles show evidence of the defendants’ fingerprints?”

“No, sir.”

“No?” Savidge put on a show of being surprised. “Well, then, on which of the bottles did you find the defendants’ fingerprints?”

“None, sir.”

Members of the jury were seen to frown. Savidge appeared even more greatly surprised. “None, Sergeant Collins? None at all? How do you account for that fact?”

“Well, sir, they might have handled the bottles with gloves, or wiped them afterward to prevent leaving fingerprints.”

“They might, I suppose, although that’s not likely, since most persons do not even know of the existence of these prints. Is there another explanation for an absence of prints?”

“Yes, sir.” The sergeant seemed perturbed. “They might not have handled the bottles at all.”

“Thank you. Yes, I think we must consider that as a possibility. Now, Sergeant, I should be most grateful if you would tell the jury whose prints you did find on these three bottles.”

Sergeant Collins took a deep breath. “There were several of Detective Finney’s finger- and thumbprints on each one, especially on the necks.”

“Mr. Baker, who performed the chemical analysis, testified that he wore gloves when he handled the bottles, to avoid possible burns from the nitric acid. I don’t suppose you found his prints?”

“No, sir.”

“Right. Well, then, were there any other fingerprints-other than those belonging to Detective Finney, I mean?”

“Yes, sir. There was a partial fingerprint on the bottle found in Mr. Gould’s room.”

“That would be Exhibit B3. And where on the bottle did you observe this partial print?”

“Adjacent to the identifying label.”

“That would be the label that Detective Finney applied. In fact, it is possible to see only half of the print, is it not?”

“Yes.”

“Where is the other half of the print to be found, then?”

“Under the label.” The sergeant seemed to speak with increasing reluctance. Charles noticed that several members of the jury were sitting forward in their seats, their attention fastened on the witness.

“And how do you know this, Sergeant?”

“The label was loose enough at the edge to permit me to lift it with a knife blade and dust the surface of the bottle.”

“If the print was under the label, that must mean-” Savidge broke off. “You’re the expert, Sergeant Collins. Suppose you tell us what it means.”

Collins’s reluctance was clear. “That the print was on the bottle before Detective Finney applied the label.”

“And Detective Finney testified that he applied the labels to the bottles as he found them in the defendants’ rooms. This print, therefore, must have been made at some point before Detective Finney discovered the bottle.”

“Yes.”

“It is mostly likely the print of the person who placed the bottle under the bed, isn’t it?”

“I suppose so,” the sergeant said. “Yes, sir.”

“And whose print is it?”

“I don’t know, sir. I did not remove the label to see the entire print.”

“You didn’t?” Savidge arched his eyebrows. “And why didn’t you remove the label?”

The sergeant dropped his glance. “I was instructed not to do so,” he said in a low voice.

Savidge leaned forward. “You were instructed not to do so. By whom, Sergeant?”

“By… by Inspector Ashcraft, sir.”

“By Inspector Ashcraft?” Savidge frowned. “I must say, I find that puzzling, since one might imagine that the inspector would be anxious to learn whatever can be learned from the fingerprints on the bottles. However, we will leave that for the moment.” He turned to the bench. “With your lordship’s permission, I should like to ask Sergeant Collins to remove the label, study the fingerprint, and tell us, if he can, the identity of its maker.”

Sims jumped angrily to his feet. “Objection! This is pure theatrical show, my lord. And most irregular.”

The judge sighed. “Theatrical, yes. Irregular, perhaps. However, I see no reason why the fingerprint evidence should not be obtained, since it seems to be germane to the question of who handled the bottle. The defense may proceed.”

Sulkily, Sims dropped back into his chair. Sergeant Collins left the witness box and went to the table where the exhibits were displayed. With a thin-bladed knife, he lifted the edge of the label and peeled it off. Taking a fingerprint kit out of his pocket, he dusted the print with a black powder, revealing it to be continuous under the label. Savidge handed him a magnifying glass.