“That’s right.”
“That’s a national average.”
“Right.”
“But that doesn’t tell you how many people with those characteristics live in the state of Oklahoma, does it?”
“Not specifically, no.”
“And it certainly doesn’t tell you how many people with those characteristics live in the Tulsa area, does it?”
“Using the national statistical map as a guide, I can—”
“Doctor, please answer the question. Your national statistics cannot tell us with any certainty how many people with these blood characteristics live in the Tulsa area. Right?”
“That is correct.”
“There may be five, or there may be fifty. You just don’t know.”
“Well, I haven’t taken a census, if that’s what you mean.”
“What I mean, sir, is that you don’t know. You’re just guessing.”
“On a large-scale sampling, the statistical probabilities will come out correct.”
“On a large scale, yes, but on a small scale, say, a single city, the statistics may be totally skewed, right?”
“Well… it’s possible.”
“In actual practice, statistics don’t always play out the way they’re supposed to, right?”
“If the sampling is small, it’s possible—”
“Possible? Anybody who’s ever been to Las Vegas knows that statistical probabilities don’t always play out according to the book.”
“Yes, but the point—”
“The point, sir, is that you’ve told this jury there are only five people in town whose blood matches the sample you found, but the truth is, you don’t know how many possible matches there are. Right?”
“I can perform a probability analysis—”
“Answer the question, sir. The truth is, you don’t know how many people in this city have blood that matches your sample. Correct?”
Camilieri’s lips pursed tightly together. “That’s correct.”
“Thank you, sir. I appreciate your candor.” Ben flipped a page in his notebook. “For that matter, there’s no reason to assume that the killer resides in the Tulsa metropolitan area, is there?”
Camilieri glanced up at Barrett. “Well …”
“Doctor, do you know who the killer was?”
“Well, not from my own personal knowledge, no.”
“So therefore, you don’t know where the killer lives, either.”
“I suppose.”
“So there was no reason to limit your blood analysis to Tulsa. You just did that as a means of justifying a smaller statistical base.”
“I did that because it seemed probable.”
“Are you a detective, sir?”
“No, of course not.”
“Is it your job to detect?”
“No.”
“Then don’t.” Ben quickly checked the judge. He was getting a bit rowdy even by defense attorney standards. “Did you uncover any evidence that suggested where the murderer lived?”
“No.”
“Then please don’t suggest to the jury that you did. The decision to limit your statistical base to the Tulsa area was an arbitrary decision on your part, right?”
Camilieri seemed resigned to the inevitable. “That’s correct.”
“Thank you.” Ben knew that was as good as it was going to get. Time to move on.
“Did you find any other traces of blood anywhere in the Barrett home other than those you’ve mentioned?”
“I found blood on or near each corpse, and some mixed with smeared footprints in the front hallway.”
“Anything else?”
“Well, there was one small sample in Mrs. Barrett’s bed, but I hardly thought that relevant, since none of the murders occurred there.”
“Now, you admitted yourself that it was not possible to make a positive identification of any particular suspect simply by comparing blood samples.”
“That’s true.”
“So even with all your statistics, you cannot say with certainty that the blood you found on Caroline Barrett came from her husband, correct?”
It seemed Camilieri had had enough. “Well, given the circumstances, it seems damned likely.”
“Ah. So you, like everyone else on the police force, went into your analysis assuming my client was guilty and looking for ways to prove it.”
“I wouldn’t put it like that.”
“In fact, all you can say for certain is that the blood came from someone other than Caroline Barrett, right?”
Camilieri sighed heavily. “Yes. That’s what I said.”
“But you did consider the circumstances when you made your analysis. You said so yourself.”
“Right.”
“As to any other conclusion, even you must admit there is some element of … doubt.”
“Objection!” Bullock rose to the occasion. “This is improper.”
Judge Hart nodded. “I believe I will ask you to rephrase that question, counsel. This isn’t closing argument.”
“That’s all right, your honor.” The point was already made, as well as it was likely to be made with this witness, anyway. “Doctor, I believe your exact testimony was that the blood samples taken from Caroline Barrett and my client were an almost perfect match.”
“That’s correct.”
“Not a perfect match, but an almost perfect match.”
Camilieri spread his hands wide. “Well, you have to be realistic. Blood is not static. Minute changes occur every second it pulses through your veins. If I took two samples from you today, one now and one half an hour later, they would not match each other perfectly.”
“Did you figure these … imperfections into your statistical analysis?”
“How do you mean?”
“Well, you told the jury that only five people in Tulsa could make a perfect match with the blood taken from Caroline Barrett. How many could make imperfect matches?”
“That’s an absurd question.”
“Is it? What’s the degree of variation between the sample taken from the crime scene and the sample taken from my client?”
Camilieri twitched. “About six percent.”
“Six percent!” Ben said it as if it was enormous, although he had been hoping for a larger number. “How many people in Tulsa have blood that would come within six percent of matching the sample you found at the scene of the crime?”
“I don’t know.”
“But it would be more than five.”
“Ye-es.”
“Substantially more.”
Camilieri took another deep unhappy breath. “Yes. Substantially more.”
“In the hundreds?”
“I … suppose.”
“In the thousands?”
“It’s … possible. I’d have to run an analysis.”
“Thank you, Doctor. I believe I see the suspect pool expanding right before my eyes.” Ben flipped another page in his notebook. He’d done enough on statistics. Surely the jury had some idea now how misleading they could be. Time to hammer again on his main theme. “Doctor, you said there were no spectators at the crime scene when you arrived, correct?”
Camilieri seized the opportunity to try to do the prosecution some good. “That is absolutely correct.”
“But in fact you did not arrive until after Lieutenant Morelli did. Right?”
“That’s … right.”
“And as he told us, he chased off the spectators when he got there.”
“I wouldn’t know.”
“Well, now, that’s the truth of the situation, isn’t it? You don’t know whether unauthorized personnel were at the crime scene before you. Right?”
“I don’t know what occurred before I got there, no.”
“Similarly, you don’t know whether there was any contamination of the blood evidence—before you got there.”
“I saw no evidence of it.”
“But you wouldn’t, would you? Because you arrived after the damage was already done.”