Gabriel showed a succession of slides of bone marrow, each of them at a higher magnification, revealing pari passu more and more detail in the nucleus of a marrow cell, the final slide showing that it looked like a string of thin sausages.
“This marrow cell is supposed to be from a male mouse. Yet you can see that its nucleus is very segmented, which is more in keeping with it being from a female mouse.” He waved again toward the screen. “All the other tissues from this mouse contained cells in which this change was not seen, indicating to Anna they were most likely from a male mouse.” Gabriel showed a succession of microscopic images of cells from liver, kidney, lung and testis to illustrate his point, before summing up, “There’s a sex mismatch that’s only evident in slides of the bone marrow in about ten or so of the PLF-treated animals”
“Of course, what you say doesn’t mean that PLF has a damaging effect on the marrow,” said Hewitt, finally coming to life. “Only that the slides were somehow mixed up. After all, they all show normal marrow.”
“But they weren’t mixed up in the first batch of experiments when an equal number of female and male mice were given the high dose of PLF and the cells in all the tissues did or did not contain a Barr body respectively. And it was in that experiment Anna Taylor originally noticed the marrow abnormality.”
Palmer now spoke. “None the less, Hewitt is right. The slides are most likely mislabelled. The pathology technicians who process the tissues may have mixed up some of the specimen pots. I imagine it’s easily done. You did say that you noticed a sex mismatch only in some experiments?”
“That’s right.”
“And that PLF did not appear to have a damaging effect on female or male marrow in all but that troublesome first experiment?”
“Right.”
“Then, I don’t see a problem. We just have to match up the slides of marrow to the correct mice, be they male or female.”
“I don’t believe it’s quite that simple, Ken. And Anna Taylor didn’t think so either.”
“What do you mean?” asked Frances Hewitt.
“You see, it’s not easy to tell the difference between male and female mice just by looking at them running about in their cages. Even animal house workers can have trouble spotting whether male genitalia are present or not. They’re small and rather discreetly well hidden, as Gearing would say.”
“But if all the marrow slides are normal I can’t see where all this is leading?” Palmer said impatiently.
“But they weren’t all normal. Not in the first experiment anyway when I examined all the tissues and found there was no sex mismatch. Nor did Anna. That’s on record. And I believe it must have been the same in the last experiment.”
“But you said...” Frances Hewitt began.
“I said that the slides of bone marrow appeared to show a sex-mismatch in some experiments. That includes those of the last experiment Anna was examining when she was murdered. That’s what you can see on the screen now. This bone specimen was supposed to be from a male mouse but, as you can see, the nuclear changes indicate that the specimen must have come from a different mouse — a female one. It struck me as strange that should be the case, given that Anna was very particular about sampling the tissues herself in that last experiment. You see, I’m sure she suspected that someone didn’t want her to see the effect of PLF on marrow cells and was deliberately substituting bogus specimens of normal bone.”
So,” said Liz Reynolds, “you’re saying that whoever killed Anna Taylor knew that she was reviewing all the slides and that she had discovered the fact that they had been tampered with.”
Gabriel nodded. “Which brings us to the next question — at what stage did the substitution occur? I checked the blocks from which the slides of all the tissues except those of the last experiment were cut. These appeared to come from the Nebotec lab. The blocks had the orientation mark which Vishant Samant and Tina Simms, being the good technicians they are, put on them to ensure that they are always cut in the same direction. There was also no difference in the type or intensity of the stain used on the slides. So it looked as if everything had been processed at Nebotec. That meant the tissues and not the slides had been substituted.
“Perhaps Anna made the same checks and came to the same conclusion. It was for this reason she made sure that in the last experiment she sampled all the tissues from the mice herself. Usually she let the technicians do the sampling. Whoever killed her knew that and realised that the game would be up as soon as she examined a slide of bone marrow from a PLF-treated mouse and saw the same myeloproliferative change she’d spotted in the first experiment.”
There was a short silence like that between applause and the end of performance before Gabriel spoke again. “Who could have had access to mouse tissues and had the ability to alter the results? Samant certainly had both.”
Samant noisily shifted his position.
“But it is difficult to see why he would have done so. He probably wasn’t privy to the results that were being generated and so wouldn’t have known which slides to change. He had fallen out of favour with Anna when she saw how he treated his wife and children. He could, of course, have been acting for another party, possibly Hewitt, Taylor or Palmer. On the evening when Anna Taylor was murdered Samant had cycled back past Nebotec after buying lottery tickets from the newsagent’s. He told Brook that he saw a figure, most likely Hewitt, cross from the Nebotec laboratory back to the office block after 5.00. This was useful knowledge and he approached Hewitt after Anna’s death and began blackmailing him. Samant wasted no time, buying a new television with the money.”
“No, no, I asked for a loan from Mr Hewitt,” Samant spoke up.
Gabriel ignored the interruption.
“Of course, these facts put Hewitt well and truly in the picture. But it is difficult to see how Hewitt could have murdered Anna Taylor. Whoever killed her would inevitably have had some evidence of blood on their clothing. Not just a little blood, but quite a lot according to Grant and Brook. It’s not easy to explain how Hewitt could have got rid of his blood-stained clothing and found time — he met with Matt Taylor at 5.30 — to drop Anna’s purse outside the lab on the cycle path and somehow get rid of her ring and necklace as well as the boots we know the murderer wore. He could have had help from his wife but there is no evidence to suggest that she came to Nebotec that evening. It was she though who dealt with Samant’s demands, paying him money to say nothing about her husband’s visitation to Anna Taylor that evening.”
Frances Hewitt looked stonily at Gabriel but said nothing. “Of course, Matt Taylor was also there that evening,”
Gabriel continued. “His work meant that he spent a lot of time in the animal house, injecting experimental animals. He certainly had access to normal animal tissues which he could have substituted for those from PLF-treated mice. And he had good reason for wanting the PLF palindrome work to be successful. It was essentially his life work: the subject of his D.Phil thesis and the focus of his current work at Nebotec. He saw it as his future too. He had taken out a patent on MT-1, the palindrome sequence that he had discovered with Palmer in pre-Nebotec days. That research had not progressed because it was noticed that the palindrome protein was expressed in normal as well as cancer cells. Liz Reynolds had, in fact, been the first to make that observation when she worked with Palmer and Forsyth. Palmer had excluded her results from the Nature paper that was published, something that understandably rankled her.”
“They were our results,” Liz said. “Palmer travelled the world, saying that they were all his work. But he took them from Matt and me. It wasn’t Matt’s idea to take out the patent. It was mine. I just wanted to protect him.”
“And you continued to support Matt Taylor’s work on the great palindrome project even after he married Anna. The prize was great: a drug to cure cancer. That also appealed to Anna, who was ambitious to make a name for herself in science.”
“Something she no doubt thought that she wouldn
’t if she continued to work with you,” said Palmer sharply.
“Perhaps you’re right, Ken. But then I prefer my science to add something to knowledge not just the balance sheet of a company.”
“That goes without saying.”
“If so, then you should have said it more often to Anna Taylor because I believe she didn’t trust your results or even think they were that new. You thought you had a tame pathologist who would just rubber stamp your results. Not make a fuss. Instead you had a real pathologist. She wasn’t in awe of you, like Matt Taylor. She knew how to take care of herself and was prepared to override you. She didn’t think twice about going over your head straight to Hewitt to get things done.”
“And you think she was completely innocent in all this?” said Frances Hewitt. “She knew what she was doing.”
“Frances, I told you a thousand times...”
“Then why did you go and see her that evening?” Gabriel asked.
“I bumped into her that afternoon and she asked to see me before I went over the data with Matt Taylor.”
Frances Hewitt closed her eyes and made a dismissive noise in her throat.
“I’m inclined to believe your husband, Mrs Hewitt. I suspect Anna told you her findings when you went to see her.”
Hewitt bowed his head and nodded. “It was a complete shock to me. It holed our FDA application below the water line. I asked her not to say anything to anyone before I had a chance to speak to Ken. I said I’d ring her later. But then, when Matt came back after seeing me, it was too late. I didn’t know what to do.”
“So you rang your wife and she told you to say and do nothing. And particularly to say nothing to the police.”
He nodded.
“And she took care of Samant when he came out of the woodwork and threatened to expose your story as a lie.”
“But I didn’t kill her. You said yourself it was unlikely.”
“And it was unlikely for another reason. I said that all the blocks up to the last experiment had the orientation mark that Samant and Tina put on them. Most of those in the last experiment did as well. The exceptions were the blocks of bone in which the marrow cells exhibited these inconsistent nuclear features.
“Someone had replaced these blocks in the file, someone who hadn’t noticed or didn’t know that the technicians, after processing the specimen, put a pencil mark in the top right hand corner of the block before producing the slides. Brook had Grant analyse the type of stain used to make the slide Anna was supposed to be looking at when she was murdered. It came up with an interesting result: the stain was not the same as that in the other Nebotec slides but identical to that used in the Pathology Department here in this hospital. Chambers, my chief technician, told me he had noticed that some items in the lab had gone missing and that there had been some use of the processing equipment after hours. It is very likely that whoever killed Anna Taylor produced the substitute slide in this hospital.” Gabriel paused. “He also told me that Tom Duncan had gone to see him recently and asked for some work to be carried out in the lab.”
“They were for another project,” said Tom. “It was Anna’s idea. She wanted me to check the gender of the mice in some of her experiments which I did by in-situ hybridisation. She said the results were needed for a study she planned to write up and that she’d include me as an author on the paper.”
“And what did you find?”
“To be honest, I don’t know. Anna gave me the slides blind. I carried out the tests on some numbered slides and showed her the results. She said that she had to check the numbers before she was sure whether my results corresponded with hers. But she was murdered before I could find out more.”
“But that’s not all Anna told you.”
“What do you mean?”
“Didn’t she tell you that she was planning to return to academic pathology and had applied for the Clinical Tutor post you had put in for?”
Tom Duncan’s silence was an assent.
Gabriel quickly moved on, as if deliberately not letting this possibility take root in the mind of his audience.
“Of course, you didn’t know much about PLF. The actual molecular structure is a closely guarded secret for commercial reasons but I would guess that its molecular weight is very close to that of MT-1.” There was a pause. “Am I right?”
Taylor did not answer but glanced at Palmer who was looking intently at Gabriel.
Gabriel interpreted their collective silence as a positive response. “Which means that the patent Liz Reynolds and Taylor held on MT-1 was potentially quite valuable if they had chosen to challenge Nebotec’s claim that PLF was a new anti-cancer drug.”
Taylor looked up. “But that doesn’t prove anything.”
“You spent time in the animal house and in the lab the evening Anna was murdered. You said that she was alone when you left to see Hewitt. You were not covered in blood when you saw Hewitt at 5:30 but later, yes, after you said you had discovered the body, you were. But what did you do with the murder weapon? And the boots — size 12, quite large — that we know were worn by the murderer. They must have been got rid of by someone else who was there.”
There was a brief pause, an instant of silence, before Gabriel turned to Liz Reynolds and said, “Of course, it’s possible that the bicycle light spotted by Samant entering Nebotec around 5.15 was not that of Tom Duncan but yours Liz.”
Liz was silent.
“It’s possible that she told you then she had discovered the substitution of slides. That threatened the patent Matt Taylor and you were hoping to cash in on. The obstacle to that was Anna. That alone may have been sufficient motive for Taylor and you to kill her.”
Gabriel looked at his colleague directly. She coloured more in embarrassment than fear, aware that he had just stopped short of suggesting that there may have been another reason why she would have wanted to murder Anna Taylor.
“It’s not true,” was all she said in reply.
“But it is a possible scenario, isn’t it, that you killed her with a microtome knife stolen from the hospital Pathology Department and then substituted the slides of mouse bone marrow she was looking at with those you had prepared in the lab? And then with Taylor’s help you broke the window to make it look like a robbery and left via the front entrance, letting yourself out using Anna Taylor’s card? You scattered the contents of Anna’s purse outside Nebotec and then cycled back to Oxford where Gearing saw you in a great hurry at 6.00. The substitution of the slides and blocks, and the whole business of making Anna Taylor’s murder look like a robbery could be carried out more quickly and easily by two people.”
There was a silence of expectation, a pause that was prolonged until it was almost painful.
“I wasn’t there. All I knew was that Anna was worried about how you’d feel about her returning to the department. I wanted to go out there to speak to Matt and her, but I just didn’t have time before my tutorial at the college. I didn’t know about the slides. She never said anything about them to me. And from what Matt’s told me, he didn’t know either.”
Gabriel paused for a moment as if considering whether to dispute her words before continuing.
“You know, the one thing I was never able to understand from the beginning about this whole business was a letter I received from Anna about the Clinical Tutor job. She wrote to me at home and not at work and I couldn’t understand why she did that. Then it dawned on me that she didn’t want someone who was a member of our department to spot her letter. Of course, that person could have been you Liz. But then it doesn’t make sense that Anna would have contacted you about the Clinical Tutor job if she feared that you were working against her. No, it had to be someone else in our department that she didn’t want to see her letter, someone whom she didn’t want to know that she was planning her exit from Nebotec. And the only person I can think that could be is you Ken.”
“Aren’t you forgetting a rather important fact, Gabriel,” Palmer said stiffly. “I w
asn’t there at the time. I was at Heathrow, catching a plane to Edinburgh.”
Gabriel didn’t seem to hear. He was looking towards the back of the lecture theatre, to the blacked out projection room where the movement of some figures had caught his eye.
“What are you looking at?” Palmer asked, looking at him archly.
Gabriel ignored the question. “You know, Ken, most pathologists don’t need palindromes to identify a malignant tumour. They can tell a cell is malignant just from the look of it.”
“I wasn’t there if that’s where all this melodrama is leading us,” Palmer said coolly.
“But you were and I know why you had to be. When you realised that Anna Taylor had noticed an abnormality in the bone marrow of the first batch of mice treated with PLF, you systematically began to substitute bone specimens of PLF-treated mice with those from normal mice in the Nebotec animal house. What you didn’t realise was that the sex of some of the mice from which you took the bones was not always the same as that of the PLF-treated mice. It was Anna who spotted that. You almost got away with it too. It was only her insistence on repeating the experiment one last time and personally following it through, sampling the tissues herself, that stopped you. It was then you realised that urgent action was needed to rescue all the years of work you had put into the palindrome project. And so you cut and processed a few samples of normal bone in the hospital laboratory yourself then made the substitution after murdering her. And you planned it so that it would look as if you were out of the department at the time Anna was murdered.”
Palmer said nothing. Not that Gabriel expected an answer; in a way he preferred the futility of Palmer’s silence, hoping for a cumulative effect, an internal pressure that would build up and finally explode into words.
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