Lucia de Berk

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Lucia de Berk (born The Hague, Netherlands 22 September 1961), in the Dutch media generally called Lucy de B. or Lucia de B., is a Dutch nurse who was sentenced to life imprisonment in 2003 for four murders and three attempted murders on patients in her care. After an appeal she was convicted in 2004 of seven murders and three attempts. Her conviction is controversial among the media and scientists and has been questioned by investigative reporter Peter R. de Vries.

Contents 1 The case of Lucia de B. 1.1 Life sentence 2 Doubts 2.1 Chain-link proof 2.2 Statistical proof 2.3 The Diary 2.4 The Dutch Forensic Institute (NFI) report 2.5 Posthumus II Commission 3 See also 4 References 5 Bibliography 6 External links

[edit] The case of Lucia de B.

As a result of an unexpected and unexplained death of a baby in the Juliana Children's Hospital (JKZ) in The Hague, The Netherlands, on 4 September 2001, earlier deaths and resuscitations were scrutinized. 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 the licensed child nurse.

[edit] 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 for the attempted murder of three others. The verdict depended in part on a statistical calculation, according to which, allegedly, the probability is 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 some medical expert, other evidence was present or in which, again, according to some 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 (JKZ), the Red Cross Hospital (RKZ) 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 Lucia de Berk, who was unable or unwilling to give a reason why she 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, de Berk also received "tbs" ("terbeschikkingstelling", detention with coerced psychiatric treatment), which is a strange addition to a life sentence, when the suspect did not plead mental illness as cause of her crimes (she denied committing them), nor did the state criminal psychological observation unit find any evidence of this. The Court found this so far unique sentence necessary, despite the fact that those who are convicted to life sentences in the Netherlands are very rarely eligible for parole.

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 (NOS), and other media that followed the process, considered the withdrawal of this evidence as a huge setback for Public Prosecution Service (OM). This witness statement was the only hard evidence, and it had vanished. A series of articles appeared over the following years in several newspapers, including Vrij Nederland and the Volkskrant, doubting the safety of the conviction. It was suggested that the prosecution had manipulated evidence and the judges had drawn the wrong conclusions.

The case was next brought to the 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 the Strasburg analysis 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 13 July 2006, as expected, de Berk was sentenced by the Court of Appeals in Amsterdam to life imprisonment, with no subsequent detention in psychiatric care.

[edit] Doubts

A few persons continued to express doubts about the conviction of de Berk. 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" ^[1]. The doubts are related to the chaining-evidence argument used by the court and the medical and statistical ingredients.

[edit] Chain-link proof

Of the seven murders and three attempted murders finally attributed to de Berk by the court, only two were considered by the court proven by medical evidence. According to the court de Berk had poisoned these two patients. The court then applies a so-called chaining-evidence argument. This means that if the several (attempted) murders have already been established beyond reasonable doubt, then much weaker evidence than normal is quite sufficient to establish that a subsequent eight “suspicious incidents” are indeed suspicious and in fact are murders or attempted murders carried out by de Berk.

This is controversial, because for the two murders found proven by the court, many experts still did 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 (same) method used in those laboratories did not exclude that the substance found was actually a related substance naturally produced by the body itself (i.e., this could be a false positive, and the two measurements are not better than one). The Strasburg laboratory used a new method, sometimes referred to as the gold standard, a test of high specificity and sensitivity, and it did not reveal presence of any digoxin. In the other case, the intoxication could well have been an overdose caused by a faulty prescription. For both children, the question moreover remained, 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 timestamp on a certain monitor that at the alleged moment of poisoning Lucia was not with the patient at all, and in fact 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 defense 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, it should be pointed out that all deaths had been registerd as natural, with the exception of the last event. Even that last event was initially thought to be a death by natural cause by the doctors responsible for the child, but within a day, on being connected with Lucia and her repeated presence at recent incidents by other hospital authorities, it became an unnatural death.

[edit] Statistical proof

There is no hard proof against de Berk. She was not caught “red-handed”, and has always denied guilt. Among other things, the court made heavy use of statistical calculations to achieve its conviction. In a TV special of NOVA, November 4, 2003, ^[2] the Dutch professor of Criminal Law Theo de Roos states: "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), is also interviewed here, and states 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. The probability of one in 342 million, calculated by the law psychologist Elffers, is extremely controversial. It seems that the hospital and the prosecution had decided in advance that the deaths had been caused by a nurse; and still insist exclusively on this line of inquiry.

The use of multiplication of probabilities for the three wards by the law psychologist Elffers was incorrect: if one wishes to combine p-values (right tail probabilities) 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 (Fisher's method for combination of independent p-values).^[3][4] In the summing up after the appeal, the Court claims no longer to have used statistical arguments. This claim, which is in complete contradiction with the statement of the professor of Criminal Law Theo de Roos, cited above, that a conviction would not be possible without it, was also issued to the Dutch newspapers.

If one reads the verdict, one notices that statistical reasoning is still present everywhere ^[5]. It was considered clear that so many incidents could not have occurred by chance. Derksen has reported to the committee, chaired by the lawyer Grimbergen (which was a part of CEAS, consisting of committees for reevaluation of closed cases, chaired by Y. Buruma), that the number of incidents that occurred during de Berk’s shifts were too large, and the numbers for other nurses were too small. Correcting those figures, increases the chance to about one in fifty. The statisticians Richard Gill and Piet Groeneboom arrive at a chance of one out of nine that a nurse can experience a sequence of bad luck of the same type as Lucia de Berk ^[6]. In the judges’ summing-up, evidence is selected from many different medical experts, in order to argue that each of the incidents to be attributed to Lucia was indeed an unnatural death or near-death. Sometimes specialist A is preferred above specialist B, sometimes the other way around, sometimes another, C. In that case, C is arguably the most expert person, because he alone considered the incident unnatural. In another case there is only one expert who considers the death unnatural. He actually stated that he only has this opinion because Lucia was present and she had been present at so many other incidents. This is not mentioned in the judge’s conclusion.

Prof. Piet Groeneboom ^[7] has drawn attention to the lack of professionalism of the people who made the very strong statements of statistical nature at the start of the case (such as the chance of one in 342 million of the law psychologist Elffers) and the fact that neither the courts nor the Grimbergen committee consulted a real statistician or professor of mathematical statistics. Only after this committee had been studying the case for a whole year and had been repeatedly been addressed by the statistician prof. Richard Gill it allowed him to have a conversation with them.

Prof. Philip Dawid (professor of statistics, Cambridge, UK) says in the NOVA TV special ^[8] of September 29, 2007, about the work of the law psychologist Elffers in the Lucia de Berk case: “He 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 toxicologist professor DasGupta (University of Houston, Texas, USA) is also interviewed here, and comments on the complete lack of toxicological evidence w.r.t. the claimed digoxin intoxication.

The use of probability arguments in the de Berk case was discussed in a 2007 Nature article by Mark Buchanan ^[9]. He sums up the views of Ton Derksen as follows:

The court needs to weigh up two different explanations: murder or coincidence. The argument that the deaths were unlikely to have occurred by chance (whether 1 in 48 or 1 in 342 million) is not that meaningful on its own - for instance, the probability that ten murders would occur in the same hospital might be even more unlikely. What matters is the relative likelihood of the two explanations. However, the court was given an estimate for only the first scenario.

At the initiative of Richard Gill a petiton for a reopening of the Lucia de Berk case has been started. On November 2, 2007 the signatures, which were on the list at that time, have been presented to the Minister of Justice Ernst Hirsch Ballin and the State Secretary of Justice Nebahat Albayrak. Over 1300 people signed the petition by now. Among the people who signed the petition are many scientists from all over the world. In the Netherlands almost all professors of statistics and probability signed the petition ^[10].

[edit] The Diary

De Berk's diary also played a role in her conviction. On the day of death of one of her patients (an elderly lady in a terminal stage of cancer) she wrote that she had 'given in to her compulsion.' She wrote on other occasions that she had a 'very great secret,' and wrote that she was concerned about 'her tendency to give in to her compulsion.' De Berk stated that this referred to her passion for reading tarot cards, whereas the court decided it was evidence that she had euthanized the patients. De Berk explains that she did this in secret, because she did not believe it appropriate to the clinical setting of a hospital. 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. The daughter of de Berk, Fabiënne, explained in an interview on the television program Pauw & Witteman that some of her mother's notes in the diaries are 'pure fiction,' which she wanted to use for a thriller.

[edit] The Dutch Forensic Institute (NFI) report

After the appeal proceedings were closed, but before the judges delivered their verdict, the Public Prosecution Service received, via the NFI, a report from a prestigious forensic laboratory in Strasbourg. This had been requested by the NFI who had hoped that it would support the hypothesis of digoxin poisoning. In fact, the NFI wrote to Strasburg that they were hoping for a miracle. 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 to the final considerations of the sentence given to Mrs. de Berk.

[edit] Posthumus II Commission

In general, in the Dutch law system, cases are not re-opened unless a new fact, called "novum", is found. New interpretations by experts of old facts and data are generally not considered a novum.^[11]

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 some selected closed cases and looks for evidence of errors in the police investigation regarding "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 Strasburg analysis, and that the statistical data was biased and its analysis incorrect, and the conclusions drawn from it invalid. The commission announced on 19 October 2006 that this is one of the few cases it will consider in detail. Three wise 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 throws a different light on digoxin question.

In October 2007, the commission released its report and recommended that the case be re-opened. On the 2nd of April, 2008, De Berk was released for three months because after re-examining the death of one of her supposed victims, a natural death could no longer be ruled out. It was unclear at that time whether the prosecution would start a new case.

[edit] See also

• Serial killers in the Netherlands
• Miscarriages of justice in the Netherlands
• Sally Clark
• Prosecutor's fallacy

[edit] References

[edit] Bibliography

• Statistics: Conviction by numbers by Mark Buchanan in Nature (magazine) 445, 254-255 (18 January 2007) | doi:10.1038/445254a; Published online 17 January 2007

[edit] External links

1. Site on statistical aspects of case, by Richard Gill, Professor of Mathematical Statistics at Leiden University.
2. Full text of an article published in the Guardian (UK), by Ben Goldacre
3. English summary of site of Dutch committee for Lucia de B. by Metta de Noo and Ton Derksen
4. Three reasoning instincts and the fabrication of facts: the case Lucia de B., by Ton Derksen
5. P. Groeneboom blog, 11/1/2008, by Piet Groeneboom