“Thank you, Doctor,” Lawrence went on. “Could you tell, in this case, how the victim was strangled?”

“Yes. With a ligature. A satchel strap, in fact.”

“And was this found close to the scene?”

“Yes. It was still attached to the victim’s satchel.”

“In your expert opinion, do you have any reason to doubt it was used as the murder weapon?”

“None at all. We carried out a number of tests. The satchel strap matched the indentations in the victim’s throat perfectly. It was angled slightly upwards, cutting into the skin at the bottom part, indicating that she had been strangled from behind and that her attacker was taller than her. There was also blood around the edge of the strap.”

“How much taller was the killer?” asked Jerome Lawrence.

“The victim was five foot six, so I would put the attacker at least six inches taller, perhaps more.”

“And the accused is six foot two, as has already been established?”

“So I believe, yes.”

“Would it have required a great deal of strength?”

“A certain amount, yes. But nothing superhuman.”

“Would the manner of attack make it difficult for the victim to fight off her attacker?”

“Almost impossible. There wouldn’t be much she could do. She might manage a wild scratch, of course, or a backwards kick to the shins with her heel.”

“You mentioned a ‘wild scratch.’ Would this be possible if she were strangled from behind?”

“Oh, yes. It’s quite conceivable she might reach behind and scratch her assailant.”

“Was it possible to tell whether she had been killed in St. Mary’s churchyard or elsewhere?”

“Yes, by the extent of post-mortem lividity, such as it was. This-” he turned to explain to the jury without Lawrence’s prompting, “means that when the heart stops, the blood simply obeys the force of gravity and sinks to the lowest part of the body. It gathers and stains at points where the flesh is not in contact with the ground. Parts of the body that do remain in contact with the ground will remain white, of course, because the pressure will not allow the blood to settle in the capillaries. In this case, the staining at the back of the neck, small of the back and backs of the legs indicated that the deceased had been lying in the same position since her death. Also, as lividity was in its early stages, she couldn’t have been there for very long. It generally begins about thirty minutes to one hour after death, develops fully between three and four hours and becomes fixed between eight and ten hours. The lividity was still faint, and blanching still occurred.”

“Could you explain blanching for the benefit of the court?”

“Certainly. Before the blood coagulates in the vessels, if you touch an area of lividity it will turn white. When you remove your fingertip, it will resume its lividity. After four or five hours the discoloration hardens, becomes clotted, and pressure will not cause blanching.”

“And what does this tell you?”

“Amongst other things, it helps determine time of death. As I said, lividity had only just started and there was no sign of rigor mortis, which usually begins in the eyelids about two or three hours after death. I also took temperature readings, and based on a mathematical calculation, I came up with time of death somewhere between five o’clock and when she was discovered.”

“No earlier?”

“In my opinion, that would be very unlikely indeed.”

“And as the victim’s friend Megan Preece reports parting with Deborah near the bridge at six o’clock, and the evidence of Daniel Charters places Owen-”

“Objection!”

“Sustained.” Judge Simmonds pointed with a bony finger. “Mr. Lawrence, behave yourself. You ought to know better.”

Lawrence bowed. “Your Honor. Thank you, Dr. Glendenning. I have no further questions.”

Shirley Castle stood up to cross-examine. “I only have a couple of questions, Doctor,” she said briskly. “Minor points, really. I shan’t keep you long.”

Dr. Glendenning inclined his head and smiled at her in a gentlemanly way.

“I assume you supervised the collection of oral, vaginal and anal swabs at the crime scene?” Shirley Castle began.

“I did.”

“And did you find any traces of semen?”

“None.”

“None at all?”

“That is correct.”

“In your post-mortem examination, did you discover any signs of forcible intercourse?”

“I found no signs of any intercourse at all, forcible or otherwise.”

Shirley Castle frowned. “Yet you referred to this as a ‘sex crime’ in your earlier testimony. Does that absence of evidence not strike you as unusual in such a crime?”

“Not really. There are many kinds of sex crimes. The way the clothing was disturbed was reminiscent, in my experience, of a sex-crime scene.”

“And we have already heard your enviable credentials as an expert on such matters, Doctor. How accurate is your estimate of time of death?”

“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?”