Colin Norris - lessons for Letby?

The appeal of another killer nurse doesn't bode well for Letbyists

In a judgement handed out last week, the Court of Appeal (CoA) rejected an appeal on behalf of Colin Norris (AKA Colin Campbell). The former nurse was convicted in 2008 of injecting five elderly patients with insulin. The case has a number of similarities with the Lucy Letby case, although Letby’s lawyer has hastily retreated from drawing comparisons since the CoA rejected Norris’s appeal.

The five patients developed sudden and severe hypoglycaemia, did not respond to treatment (i.e. administration of glucose), and all but one died. Three deaths were initially put down to natural causes. Suspicions only emerged later when a fifth patient, Ethel Hall, died of sudden severe hypoglycaemia which all agree was caused by exogenous insulin being administered. Tests showed extremely high levels of insulin in her blood. Unfortunately, blood tests had not been conducted on the other four patients.

Norris’s appeal was based on the claim that the other four sudden collapses/deaths were natural and somebody else did the murder. The argument is that he was convicted of killing Mrs Hall because he was implicated in the cases of the other four patients and had happened, coincidentally, to have predicted the exact time when she would collapse. He was the only person who had the opportunity to attack all five patients, but without the first four incidents, it is argued, he wouldn’t have been convicted of murdering Mrs Hall (there was at least one other person who could have killed her).

Two new experts - Dr Croxson and Dr Hopkins - say that the hypoglycaemia of the first four patients could have been natural and that old age and frailty are risk factors for hypoglycaemia. Norris’s lawyers argued that science has moved on since Norris was convicted in 2008 and pointed to three other deaths, for which Norris was not accused of murder, which were similar to those of Norris’s victims but for which blood tests proved that the insulin was produced endogenously, i.e. naturally.

Dr Croxson and Dr Hopkins both accept that sudden, severe hypoglycaemia in elderly/frail people, in the absence of either exogenous insulin (or, theoretically, insulin inducing drugs) or the specific illnesses identified as leading to such, is rare. However, as indicated above, their proposition is that severe hypoglycaemia can arise in elderly patients, in the absence of those specific conditions, from a combination of general frailty and some of the range of disorders or diseases of age: termed the ‘co-morbidities’ as shorthand deployed during the hearing of the appeal. The proposition is that age and frailty can lead gradually to a ‘tipping point’ where the body’s control of glucose and insulin fails.

But the other experts the CoA heard from strongly disagreed:

They have no clinical experience of such a case. They have never seen it documented. They do not accept that it arises in the literature. They do not see why it should be so.

These experts agreed that “frail, elderly people can sometimes develop hypoglycaemia” but said it will be of “gradual onset, usually mild and will not be profound”, which was not the case with Norris’s patients. They say that frailty and the ‘co-morbidities’ of age are not, in themselves, risk factors for hypoglycaemia and they had never seen such a case in their own clinical practice.

Nor does the medical literature give much support to the theory. The CoA said:

From our own independent review, we find that the medical literature does not authenticate Dr Hopkins’ hypothesis

The Court of Appeal rejected the hypothesis on the basis that it had little evidential support and rejected it as an explanation for the four deaths on the basis that it did not fit the clinical picture of the patients.

We arrive at that conclusion satisfied that the expert witnesses called by the respondent have, without misunderstanding the facts or the science and within the legitimate parameters of their respective expertise, responsibly interrogated the hypothesis against the facts with an open mind and understanding of their obligation to inform the Court of any change of opinion. In so far as they have conceded a theoretical possibility, this does not advance the appeal.

Realistically, the hypothesis cannot be ethically tested, but neither is it established by any clinical experience and nor has it been subject to peer review and publication.

They also rejected the evidence of the three other patients who had hypoglycaemia but were not treated by Norris. They said that their symptoms were quite different and that, unlike Norris’s victims, they responded to treatment. Their cases were so different, in fact, that they only served to underline how unusual the hypoglycaemia of Norris’s victims had been.

For good measure, they also disagreed with the argument that Norris wouldn’t have been convicted of Mrs Hall’s death unless he had been accused of the other murders. And so, in conclusion…

We have no doubt about the safety of any of the five convictions. The appeals are dismissed.

What, if anything, does this tell us about how Letby’s appeal is likely to proceed? The Criminal Cases Review Commission (CCRC) explained their reasons for passing the case to the CoA as follows:

“The case against [the appellant] was wholly circumstantial, and was heavily reliant on expert opinion evidence. There was very little evidence specifically inculpating him in the murder of Mrs Hall, except insofar as it could be argued that, taken together, the cluster of cases pointed towards his involvement. ...

The CCRC has decided to refer [the appellant’s] convictions based on fresh expert evidence from Professor Vincent Marks (who was instructed by [the appellant’s] representatives) [Marks was terminally ill by the time of the appeal and was replaced by Dr Hopkins - CJS] and Dr Simon Croxson (whom the CCRC instructed).

Professor Marks and Dr Croxson do not agree on every point, but they agree that insofar as each of the four patients exhibited hypoglycaemia, that condition may be accounted for by natural causes.”

There are obvious similarities with the Letby case, both in the case itself (“wholly circumstantial” and “heavily reliant on expert opinion evidence”) and in the grounds for appeal (“based on fresh expert evidence”).

The CoA heard from many experts…

Over the course of 12 days we heard evidence from Dr Hopkins, consultant physician and diabetologist and Dr Croxson, consultant geriatrician with an interest in diabetes, in support of the appeal; and Professor Heller, professor of clinical diabetes, Professor Semple, professor of translational molecular medicine, Dr Kroker, consultant physician and geriatrician, Professor Ferner, honorary consultant in general medicine and clinical pharmacology and Professor Hall, professor of clinical cardiology.

Other experts prepared reports for the appeal but were not required to be called for cross examination: Dr Cowling, consultant in microbiology and infection control, Dr Lumb, forensic pathologist, Dr Morley, consultant clinical pathologist and forensic toxicologist, Professor Vanezis, forensic pathologist and Dr du Plessis, consultant neuropathologist.

And the CoA accepted Hopkins’ and Croxson’s arguments/evidence as being sufficiently ‘new’ for an appeal.

We were not prepared to assume from our reading of their several reports, that the ‘new’ evidence was “analogous to a re-packaging of evidence that was before the jury and cannot be said to present a compelling new perspective.”

It should be first be noted that the CoA was never going to call for a retrial just because some reputable experts questioned the verdict and believed there could be an innocent explanation for the four deaths. Nor did they play a credentialist game of Top Trumps to decide who was best qualified and therefore most likely to be correct. This is worth pointing out because many Letbyists seem to think that the “world leading” (according to whom?) neonatologists on Shoo Lee’s panel will automatically be taken more seriously than all the experts from various different fields who testified under oath in the original trial.

That is not how it works. The judges felt perfectly confident dealing with medical evidence and scientific terminology before making their own minds up about which competing theory best explained events.

One of the obvious similarities between the Norris and Letby cases is the use of insulin as a murder weapon by a nurse (see also Victorino Chua and Beverley Allitt). The big difference is that insulin poisoning in the Norris case was inferred from the patients’ clinical condition whereas there was definitive proof in the case of Baby F and Baby L in the Letby case. Letbyists have tried all sorts of arguments to get around the very high levels of insulin and very low levels of c-peptide in these babies’ blood, but the CoA said in its judgement that…

All the experts are agreed that there is only one route to absolute certainty of insulin poisoning: where high levels of insulin are found in the bloodstream, with no corresponding levels of a substance known as c-peptide, then the insulin in that blood is manufactured (exogenous) rather than naturally arising (endogenous).

This doesn’t bode well for Letby. Her supporters have tried claiming that the test results were wrong, but this was discussed at length in the original trial and there is no reason to believe it. That the tests would be wrong twice is incredibly unlikely and would add a further implausible coincidence to the constellation of implausible coincidences that plagued the World’s Unluckiest Nurse in 2015-16. (In fact, Letby was incredibly lucky that the test results never made it to the consultants and were instead seen by junior doctors who didn’t recognise their significance.)

Shoo Lee’s report takes a different tack, claiming that levels of c-peptide in the babies - which were so low as to be “undetectable”, according to the scientist who conducted the tests - were not particularly low. It is hard to see that standing up in court. It is also hard to believe that the CoA will consider many of the alternative explanations in the Lee report as being new evidence since many of them were raised and rejected in court. (Off the top of my head, the claims they make about Babies A, B, F, G, K, L and O will be booted out immediately.)

Norris at least managed to get the CCRC to pass his case to the CoA. It is far from clear that Letby will be so lucky despite the ongoing PR campaign designed to put pressure on the CCRC. Unlike Letby, Norris has a lawyer who has an enviable track record of getting people out of prison (Michael Mansfield KC).

The judges at the CoA were clearly aware that Letbyists were watching the Norris appeal with interest…

Some observers have made clear in their applications to follow the proceedings by CVP that they seek to draw parallels between this case and other similar cases that may be ongoing. We make clear that we have each contributed to writing this judgment mindful of the necessity to explain the decision we reach, which has been dependent upon our view of an intricate debate between eminent scientists, by identifying the relevant issues and addressing them in terms of an appeal against conviction in the circumstances of this case.

What should those who are following proceedings infer? On the one hand, the CCRC thought that Norris’s appeal - which, like Letby’s, involved experts arguing that what we thought were murders were actually natural deaths - had enough merit to be heard by the CoA. On the other hand, the CoA rejected it on every ground, largely because the hypothesis of the new experts did not align with the medical evidence.

Will this make the CCRC more or less likely to hand over a similar case to the CoA? If they thought Norris’s appeal had enough merit, they might well think the same about Letby’s, but they might equally assume that an appeal similar to Norris’s will be firmly rejected in the same way and for similar reasons. And I suspect they would be right.