Lucia de Berk
Lucia de Berk, often called Lucia de B., is a Dutch licensed paediatric nurse, who was the subject of a miscarriage of justice.
In 2003, she was sentenced to life imprisonment for four murders and three attempted murders of patients in her care. In 2004, after an appeal, she was convicted of seven murders and three attempts. Her conviction was controversial in the media and amongst scientists, and was questioned by investigative reporter Peter R. de Vries. In October 2008, the case was reopened by the Supreme Court of the Netherlands, as new facts had been uncovered that undermined the previous verdicts. De Berk was freed, and her case was re-tried; she was exonerated in April 2010.
Charges
As a result of an unexpected death of a baby in the in The Hague on 4 September 2001, earlier deaths and cardiopulmonary resuscitations were scrutinised. Between September 2000 and September 2001 there appeared to have been nine incidents, which earlier had all been thought unremarkable but now were considered medically suspicious. Lucia de Berk had been on duty at the time of those incidents, responsible for patient care and delivery of medication. The hospital decided to press charges against de Berk.Life sentence
On 24 March 2003, de Berk was sentenced by the court in The Hague to life imprisonment for the murder of four patients and the attempted murder of three others. The verdict depended in part on a statistical calculation, according to which the probability was allegedly only 1 in 342 million that a nurse's shifts would coincide with so many of the deaths and resuscitations purely by chance. De Berk was however only sentenced in cases where, according to a medical expert, other evidence was present or in which, again according to a medical expert, no natural causes could explain the incident.In the appeal on 18 June 2004, de Berk's conviction for the seven murders and three attempted murders was upheld. The crimes were supposed to have taken place in three hospitals in The Hague: the Juliana Child Hospital, the Red Cross Hospital and the Leyenburg Hospital, where de Berk had worked earlier. In two cases the court concluded that there was proof that de Berk had poisoned the patients. Concerning the other cases the judges considered that they could not be explained medically, and that they must have been caused by de Berk, who was present on all those occasions. The idea that only weaker evidence is needed for the subsequent murders after two have been proven beyond reasonable doubt has been dubbed chain-link proof by the prosecution and adopted by the court. At the 2004 trial, besides a life sentence, de Berk also received detention with coerced psychiatric treatment, though the state criminal psychological observation unit did not find any evidence of mental illness.
Important evidence at the appeal was to be the statement of a detainee in the Pieter Baan Center, a criminal psychological observation unit, at the same time as Lucia de Berk, that she had said during outdoor exercise: "I released these 13 people from their suffering". However, during the appeal, the man withdrew his statement, saying that he had made it up. The news service of the Dutch Broadcasting Foundation and other media that followed the process considered the withdrawal of this evidence to be a huge setback for Public Prosecution Service. A series of articles appeared over the following years in several newspapers, including Vrij Nederland and the Volkskrant, raising doubts about the conviction.
The case was next brought to the Netherlands Supreme Court, which ruled on 14 March 2006 that it was incorrect to combine life imprisonment with subsequent psychiatric detention. Other complaints were not taken into consideration, and the evidence from a re-analysis by a Strasbourg laboratory was not considered relevant. The Supreme Court gave the matter back to the Court in Amsterdam to pass judgement again, on the basis of the same factual conclusions as had been made before. Some days after the ruling of the Supreme Court, de Berk suffered a stroke and was admitted to the hospital of Scheveningen prison. On July 13, 2006, de Berk was sentenced by the Court of Appeal in Amsterdam to life imprisonment, with no subsequent detention in psychiatric care.
Doubts
A committee of support for Lucia de Berk was formed that continued to express doubts about her conviction. Philosopher of science Ton Derksen, aided by his sister, geriatrician Metta de Noo-Derksen, wrote the Dutch language book Lucia de B: Reconstruction of a Miscarriage of Justice. They doubted the reasoning used by the court and the medical and statistical evidence that was presented. See also the English-language article Derksen and Meijsing.Chain-link proof
Of the seven murders and three attempted murders finally attributed to de Berk by the court, the court considered two of them to be proven by medical evidence. According to the court, de Berk had poisoned these two patients. The court then applied a so-called chaining-evidence argument. This means that if the several attempted or actual murders have already been established beyond reasonable doubt, then much weaker evidence than normal is sufficient to establish that a subsequent eight "suspicious incidents" are murders or attempted murders carried out by the same defendant.For the two murders found proven by the court in The Hague, many experts do not exclude a natural cause of death. In the case where digoxin poisoning was alleged, and supposedly detected by independent measurements in two Dutch laboratories, the method used in those laboratories did not exclude that the substance found was actually a related substance naturally produced in the human body. The Strasbourg laboratory used a new method, a test of high specificity and sensitivity, and did not support the digoxin overdose hypothesis. In the second case, the intoxication could have been an overdose caused by a faulty prescription. For both children, it was not clear how and when de Berk was able to administer the poison. Regarding the digoxin case, the prosecution gave a detailed reconstruction of the timing. However, other parts of the evidence discarded by the prosecution showed by the time-stamp on a certain monitor that at the alleged moment of poisoning de Berk was not with the patient at all, and that the specialist and his assistant were with the patient at that time.
The prosecution initially charged de Berk of causing thirteen deaths or medical emergencies. In court, the defence was able to show definitively that de Berk could not have been involved at all in several of these cases. For instance, she had been away for several days; the idea that she was there was due to administrative errors. Furthermore, all deaths had been registered as natural, with the exception of the last event. Even that last event was initially thought to be a death by natural causes by the doctors responsible for the child; but within a day, on being connected by other hospital authorities with de Berk and her repeated presence at recent incidents, it became classified as an unnatural death.
Statistical arguments
The court made heavy use of statistical calculations to achieve its conviction. In a 2003 TV special of NOVA, Dutch professor of Criminal Law Theo de Roos stated: "In the Lucia de B. case statistical evidence has been of enormous importance. I do not see how one could have come to a conviction without it". The law psychologist Henk Elffers, who was used by the courts as expert witness on statistics both in the original case and on appeal, was also interviewed on the programme and stated that the chance of a nurse working at the three hospitals being present at the scene of so many unexplained deaths and resuscitations is one in 342 million.This value was wrongly calculated. If one wishes to combine p-values of the statistical tests based on data from three separate wards, one must introduce a correction according to the number of tests, as a result of which the chance becomes one in a million.
Biased reporting meant that even this lower figure was invalid. Events were attributed to de Berk once suspicions began to fall on her, which could not have had anything to do with her in reality. The statisticians Richard D. Gill and Piet Groeneboom calculated a chance of one in twenty-five that a nurse could experience a sequence of events of the same type as Lucia de Berk.
Philip Dawid, Professor of Statistics at the University of Cambridge, stated that Elffers "made very big mistakes. He was not sufficiently professional to ask where the data came from and how accurate the data were. Even granted the data were accurate, he did some statistical calculations of a very simplistic nature, based on very simple and unrealistic assumptions. Even granted these assumptions, he had no idea how to interpret the numbers he got".
The use of probability arguments in the de Berk case was discussed in a 2007 Nature article by Mark Buchanan. He wrote:
At the initiative of Richard D. Gill, a petition for a reopening of the Lucia de Berk case was started. On 2 November 2007 the signatures were presented to the Minister of Justice, Ernst Hirsch Ballin, and the State Secretary of Justice, Nebahat Albayrak. Over 1300 people signed the petition.
Diary
Lucia de Berk's diary also played a role in her conviction. On the day of death of one of her patients she wrote that she had 'given in to her compulsion'. She wrote on other occasions that she had a 'very great secret' and that she was concerned about 'her tendency to give in to her compulsion'. De Berk has stated that these were references to her passion for reading tarot cards, which she explains she did secretly because she did not believe it appropriate to the clinical setting of a hospital. However, the court decided they were evidence that she had euthanised the patients. According to the court, the reading of cards does not accord with a 'compulsion' nor with 'perhaps an expression of fatigue', as she described it at the time. De Berk's daughter Fabiënne stated in an interview on the television program Pauw & Witteman that some of her mother's notes in the diaries are 'pure fiction' which she intended to use in writing a thriller.Dutch Forensic Institute report
After the appeal proceedings were closed, but before the judges delivered their verdict, the Public Prosecution Service received, via the Netherlands Forensic Institute, a report from a forensic laboratory in Strasbourg on the evidence for digoxin poisoning. The report subsequently lay in a drawer of the NFI for two years, but it did turn up in time for the final evaluation of the case before the Supreme Court. According to the Public Prosecution, the report contained no new facts, but according to de Berk's defence the report proved that there was not a lethal concentration of digoxin in the first case. The Supreme Court accepts the facts reported by the judges at the appeal court, and is concerned only with jurisprudence and correctness of the sentence, given those facts. The report therefore was not admitted into the final considerations of the sentence given to de Berk.Posthumus II Commission
In general, in the Dutch legal system, cases are not re-opened unless a new fact, called a novum, is found. New interpretations by experts of old facts and data are generally not considered a novum.In spite of this, Ton Derksen submitted his and Metta de Noo's research on the case to the Posthumus II Commission. This ad hoc, non-permanent commission examines selected closed cases and looks for evidence of errors in the police investigation indicating "tunnel vision" and misunderstanding of scientific evidence. Derksen pointed out that the medical experts who had ruled out the possibility of death by natural causes had not been given all relevant information, that the hypothesis of digoxin poisoning was disproven, in particular by the Strasbourg analysis, and that the statistical data were biased and the analysis incorrect, and the conclusions drawn from it invalid. The commission announced on 19 October 2006 that this was one of the few cases it would consider in detail. Three men, recruited by the Public Prosecution service from the full Posthumus II committee, considered the following matters, having been instructed to focus on possible blemishes in the criminal investigation:
- Whether there were also unexplained deaths when Lucia de Berk was not present, unknown to the public prosecutor.
- Whether the expert witnesses were given all relevant available information.
- Whether scientific knowledge now threw a different light on the digoxin question.
Case reopened
On 17 June 2008, the Advocate-General of the Supreme Court, G. Knigge, made a request for the Supreme Court to reopen the case. On 7 October 2008 the court acceded to his request, acknowledging that new facts uncovered by Knigge substantially undermined earlier evidence. In particular, an independent team of medical researchers with access to all available medical information had reported to Advocate-General Knigge that the death which sparked the case appears to have been a natural death. The key toxicologist of the earlier trials had agreed with the new medical findings, pointing out that at the time of the trial, the court had only given him partial information about the medical state of the child. De Berk's statements about her doings on the night of that child's death had also been shown to be correct; indeed, during the period in which the courts had earlier concluded that she must have administered poison, the baby was actually being treated by a medical specialist and his assistant.De Berk was allowed to remain free while awaiting a retrial at the Court of Arnhem, which first adjourned while further investigations were made. The public prosecution had asked for extensive new forensic investigations, but this request was turned down by the court. Instead it commissioned further independent medical investigations into the cases of two more of the children, again allowing a multidisciplinary medical team access to all possible medical data concerning the children. At a session on 9 December 2009, the court stated that new integral medical investigations of the last nine months had confirmed that the cases of Amber, Achmed and Achraf were all natural deaths/incidents. These were the only cases where there was previously claimed proof of de Berk's culpability.
The appeal hearing ended on 17 March 2010. Witnesses heard on the final day stated that the deaths at the Juliana Children's hospital were natural, sometimes caused by wrong treatment or bad hospital management, and sometimes unexpected because of faulty medical diagnosis. The behaviour of the nurses, including de Berk, during a couple of medical crises turned out to have been swift and effective, saving lives on several occasions. The Public Prosecution capitulated, formally requesting the court to deliver a not guilty verdict. On 14 April 2010, the court delivered the not guilty verdict.
It was the new finding of allegedly very high digoxin levels in autopsy blood in a child who was under the care of Lucia de Berk that resulted in her second conviction and life sentence for murder, i.e., at the 2004 appeal hearings. Moreover, this was despite it already being known at that time that digoxin levels on autopsy blood should be expected to be far higher than blood digoxin in a living patient. Living heart cells extract digoxin from the blood, concentrating it at levels up to 1,000 times the therapeutic digoxin levels in the circulating blood. Heart cells die within minutes after death, allowing this digoxin to diffuse into the blood in the heart and in the surrounding large blood vessels – the sites from which blood is extracted by pathologists for blood chemistry analysis. Moreover, the autopsy blood did not originate from a proper blood sample but was squeezed out of a piece of gauze left inside the body after two autopsies had disturbed all the organs.
Without the misinterpretation of the autopsy blood digoxin levels, there would not have been any consideration of digoxin poisoning – and no criminal investigation would have occurred. Furthermore, a chemical used in pharmaceutical natural rubber manufacture, MBT, leaches into injections. It can cause death as a cumulative toxin, or from anaphylaxis. MBT is measured as digoxin, using the test methods applied in the criminal investigations of Lucia de Berk and of a Canadian nurse, Susan Nelles.
Susan Nelles was similarly charged with murder of children by digoxin poisoning at the Toronto Hospital for Sick Children in 1981. She was not convicted because, as in the de Berk case, all the evidence was circumstantial. It was not until 1993 that the causes for high digoxin on autopsy blood were explained in the Canadian Nurse Journal. The causes of high autopsy blood digoxin are discussed thoroughly in a 2011 book, “The Nurses are Innocent – The Digoxin Poisoning Fallacy”. This book presents facts in defense of Susan Nelles which apply similarly to the false charge of digoxin poisoning directed against Lucia de Berk.