“It’s always an approximate business,” Glendenning admitted. “There are so many variables.”
“Could you give the court an example of how you might determine time of death?”
“Certainly. As I have already indicated, there are a number of factors, such as rigor mortis, lividity and stomach contents, but body temperature is often the most accurate. If the temperature at the time of death is normal-thirty-seven degrees centigrade-and it takes the body twenty-four to thirty-six hours after death to fall to the temperature of the environment, then one can make a back-calculation to the time of death.”
“Twenty-four to thirty-six hours,” said Shirley Castle, frowning towards the jury. “That’s between a day and a day and a half. That’s a rather broad margin for error, isn’t it?”
Glendenning smiled. “I did say it was an approximate business.”
“Yes, but you didn’t say how wildly inaccurate it was.”
“Objection.”
“Sustained, Mr. Lawrence.”
Shirley Castle bowed. “My apologies. Doctor, how long would it have taken Deborah Harrison’s body temperature to reach that of the environment?”
“Well, again it’s hard to say precisely. She was healthy, normal, slim, partially unclothed, and it was a moist evening, with a temperature of ten degrees centigrade. I’d say quicker rather than later.”
“Say twenty-eight hours? Twenty-six?”
“Around there.”
“Around there. Very well. Does the body cool at an even, steady rate?”
“As a matter of fact, no. It falls in a sigmoid curve.”
“And how do you arrive at time of death from temperature?”
“Glaister’s formula. In this case the victim’s temperature was thirty-five point five degrees centigrade. One subtracts this from the normal temperature of thirty-seven degrees and multiplies by one point one. The answer, in this case, is one point six-five hours. Taking the temperature of the environment into account, that becomes between one and two hours before I arrived on the scene.”
“What might affect the rate at which temperature falls?”
“It’s hard to say exactly. A number of factors.”
Shirley Castle took a deep breath and leaned forward. “But it is not hard to say, is it Dr. Glendenning, that thin people cool quicker than fat ones, and Deborah Harrison was thin. On the other hand, healthy people cool more slowly than weak ones, and Deborah Harrison was healthy. Naked bodies cool quicker than clothed ones, yet Deborah Harrison was only partially clothed. Bodies cool quicker in water than in air, yet in the humidity of the fog Deborah Harrison was subject to both. Am I right?”
“These are all relevant factors,” admitted Glendenning.
“According to evidence already given,” Shirley Castle went on, “Deborah was last seen alive at six o’clock, which rules out her being murdered earlier, wouldn’t you say?”
Glendenning raised his eyebrows. “I would say so, yes.”
“But the body was discovered by Rebecca Charters at six forty-five. Is that correct?”
“I understand so.”
“And the first police officers arrived at six fifty-nine?”
“Objection.”
“Yes, Mr. Lawrence?” Judge Simmonds asked.
“I’d like to know where Ms. Castle is going with this line of questioning, Your Honor.”
“The defense requests Your Honor’s indulgence. This will become clear in a short while.”
“Make it fast, Ms. Castle.”
“Yes, Your Honor. Deborah Harrison was last seen at about six o’clock, and her body was discovered in St. Mary’s graveyard at six forty-five. That leaves forty-five minutes during which she could have been murdered. Now according to your evidence as regards time of death, Doctor, she could have been murdered later than six-thirty, couldn’t she?”
Glendenning nodded. “Yes, she could have been.”
“In fact, death could have occurred even as late as six-forty, couldn’t it?”
“Yes. But I believe Rebecca Charters heard-”
“Please, Doctor. You should know better than that. Rebecca Charters has already admitted that what she heard could easily have been some animal or another. Now, given that nobody actually saw Owen Pierce enter St. Mary’s graveyard, and given that time of death could have occurred as late as six-forty, when Mr. Pierce was already in the Peking Moon, there is no direct evidence placing him at the exact scene of the crime at the exact time the crime was committed, is there, Doctor?”
“This is not-”
“And as no-one saw either Deborah Harrison or Owen Pierce enter the graveyard,” Shirley Castle charged on before anyone could stop her, “then it follows that Deborah could have gone somewhere else first, couldn’t she?”
“It’s not my place to speculate on such matters,” said Glendenning. “I’m here to testify on matters of medical fact.”
“Ah, yes,” said Shirley Castle. “Facts such as time of death. It’s a lot of leeway to give the definition of a fact, isn’t it, Doctor?”
“Objection.”
“Sustained. Will you get on with it, Ms. Castle?”
“I have no further questions, Your Honor,” she said, and sat down.
Very clever, thought Owen, then he turned to watch the juror who looked like a wrestler try to scratch an egg stain off his club tie.
IV
A week later, after more legal arguments and a succession of dull, minor scientific witnesses, from the fingerprint man to the officer responsible for keeping track of the forensic exhibits, Owen watched Shirley Castle intimidate the hair expert, who ended up retreating into scientific jargon and admitting that it was virtually impossible to prove beyond a shadow of a doubt that hair found on a victim’s or suspect’s clothing could be positively matched to its source.
The final prosecution witness was Dr. Tasker, biologist and DNA expert, a thin-faced, thin-haired academic of about forty, Owen guessed. He seemed to know his stuff, but there was a tentativeness about his delivery that threw Jerome Lawrence off kilter occasionally.
Owen wondered if the jury were as bored as he was by the interminable descriptions of autorads and enzyme scissors, by the testimony as to the scientific validity of polymerase chain reactions and the meaning of short tandem repeats, by the seeming hours spent describing the extreme care taken against the possibility of contamination of laboratory samples.
When Shirley Castle stood up to cross-examine the next afternoon, Tasker seemed a little in awe of her, and if Owen were not mistaken, perhaps a mite smitten, too. Maybe she realized this. Her tone, as she began, was relaxed, friendly, a little flirtatious even.
“Dr. Tasker,” she said with a smile, “I’m sure the court was most impressed yesterday with your account of DNA analysis. You would seem to have proved, without blinding us all with science, that the DNA derived from the bloodstain on Mr. Pierce’s anorak was indeed the DNA of Deborah Harrison. Is this true?”
Tasker nodded. “The DNA extracted from the dried bloodstain on Mr. Pierce’s anorak was fifty million times more likely to be hers than anyone else’s, and the DNA taken from the tissue sample discovered under the victim’s fingernail was fifty million times more likely to be Owen Pierce’s than anyone else’s. All we can say is how rare such a result is compared to the rest of the population.”
“Still,” smiled Shirley Castle. “Those are impressive odds, aren’t they?”
“Oh, yes.” Tasker beamed. “I certainly wouldn’t bet against them.”
“Almost beyond a shadow of a doubt,” Shirley Castle said, “And that is, after all, what this is all about, isn’t it? However, Dr. Tasker, there are one or two points you might be able to clarify for me.”
Owen swore that Tasker almost flushed with pleasure. “Of course. It would be a pleasure.”
Shirley Castle acknowledged the compliment with a slight tilt of her head. “How much of Deborah Harrison’s blood did you find on my client’s anorak?”