Death of Nobel Laureate poet and politician

Charles Brenner, PhD
February 25, 2023

The poet

Pablo Neruda, Chilean national treasure, political icon of the left, and antagonist of the usurper General Pinochet, died suspiciously only twelve days after the military coup d’etat of September 11, 1973.

Neruda genomic panel genesis

In about 2015 Dr. Cristián Orrego – Chilean, young adult during Pinochet’s coup and Neruda’s death, human rights activist, eventually with the Bay Area DOJ laboratory – recruited some scientists to explore Neruda’s death via DNA, and through his connection with and cooperation of the Chilean appeals judge Mario Carozza. He invited me because though I am a mathematician more than a scientist, he thought perhaps the mathematical approach to evidence that I contributed to another collaboration, might be applicable to the Neruda project. I was doubtful. He was persistent. In a way we were both right. If the following section explains why the evidentual strength of the C. bot discovery is not measurable objectively, that in itself is worth understanding.

Evidence

By late 2022 the genetic laboratories had confirmed the presence of sometimes lethal bacteria, Clostridium botulinum, in Neruda’s body and contamination from the environment was eliminated as an explanation. Therefore its presence is suspicious and is evidence that advances the hypothesis that Neruda was assassinated. However I do not see how such evidence could be objectively quantified.

Sometimes a mathematical – i.e. logical, objective – framework for making a decision based on evidence is possible. The framework is

Attaching numeric probabilities to subjective beliefs is a bit of a fiction or metaphor.

1. Start with some degree of belief a priori, expressed as a probability that the hypothesis is true.
2. Adjust the degree of belief up or down with each accumulated bit of evidence.
• To the extent that one can put a probability number on the “degree of belief”, there is a simple formula (Bayes’ Law) that dictates the adjustment.
3. “Proof” means belief at least as strong as some large (but always less than 100%) arbitrary decision threshold.

“Objective probability” tends to mean a probability with a scientific foundation. Pragmatically speaking it means undisputable, as opposed to “subjective probability” on which people can differ.

Such a framework can be quite useful when part of the evidence is objective, quantifiable, and is much stronger that any countervailing subjective evidence is likely to be. Matching snippets of DNA to identify a body or to decide paternity are classical examples.

One way to analogize the DNA identification model to the observation of C. bot DNA in Neruda’s tooth would be to hypothesize on the one hand that the C. bot was deliberately injected to kill, or alternatively that it was accidental from contaminated food, then imagine there is a way to calculate and compare probabilities, for each hypothesis in turn, of producing the details of the data that is actually observed. For example whether or not the molecular equivalent of live ammunition can be discerned in the data would logically be evidence one way or the other. But there is no possibility to estimate objectively how much evidence it would be.

And even if that impossibile exercise were possible, note that it does not address the a priori probability of assassination. If you agree that is a matter of opinion, then it may reasonably remain a matter of opinion in the face of the improved genomic information. For a person who, a priori, felt that the coincidence of Neruda’s death so soon after Pinochet’s coup is nearly proof by itself, the evidential increment of even slight scientific support could cross the decision threshold to proof. But another person – maybe a “two sides to every issue” type, a priori on the fence between assassination and death by cancer – would logically adjust by the same increment in the face of the scientific evidence but that would leave him still on the fence.

Whether Neruda died of botulism (or of any attack) is not yet answerable by science or mathematics.

Third hearing

This is the text of the “Executive Summary” submitted to the Chilean tribunal. It summarizes the technical reports from the McMaster University and University of Copenhagen laboratories, carefully discussed and edited and unanimiously agreed by the five authors listed. We aimed for brevity, ordinary language, and scientific neutrality. The sidebars are of course not part of the Summary. Some of them are to emphasize distinctions overlooked by some reporters.

Executive summary

Conclusions of the Forensic DNA Analyses using Next-Generation Sequencing of the Microbial Content Found in the Human Remains of Pablo Neruda, Case 1038-2011

Third International Panel of Genomic Experts

Contributions from McMaster University, University of Copenhagen, and Forensic Mathematician Charles Brenner, PhD

10 February 2023

In order to comply with the Resolution issued by Her Honor, Judge Paola Plaza González, Minister in Extraordinary Hearing of the Court of Appeals of Santiago, dated December 15th, 2022, in Case 1038-2011, 34th Crime Court, Santiago, Chile with the support of the Human Rights Program, Ministry of the Interior and Public Security, Government of Chile, to convene the International Panel of Genomic Experts III from January 24th to February 3rd, 2023, for the purpose of the investigation into the cause of the death of Mr. Pablo Neruda, the following preliminary report is presented:

I. Overview of evidence Neruda was poisoned

Analysis at McMaster University in Hamilton, Ontario, and the University of Copenhagen found Clostridium botulinum (C. bot) DNA in the teeth of the exhumed body of Pablo Neruda. Additional experiments showed that it was in his body at the time of his death, and that it did not seep into his dead body from the environment within or around his coffin. Earlier suggestions that Staphylococcus aureus was present in the body by the proteomic analyses were not supported by the DNA analyses.

The toxin responsible for botulism, a condition involving paralysis, suffocation, and possibly death, is produced by some strains of the bacterium C.bot.

“some strains”

It could be that a toxic strain of C. bot was administered to assassinate Neruda. Like many other bacteria, even non-toxic C. bot strains can trigger sepsis (blood poisoning), which is most often fatal if untreated. It is also possible that the C. bot strains found in Neruda’s remains are non-toxic strains from contaminated food ingested before death.

II. Cautions and limitations

Contrary to gossip, the genomic reports do not mean that the C. bot. strain detected in Neruda’s body is Alaska E43, nor that he was innoculated or poisoned at all.

Bacteria evolve (mutate) rapidly. Hence, there are many different strains of C. bot. The strain found in Neruda’s molar by McMaster University is confidently classified as C. bot because it is closely related to a well-known strain, C. bot Alaska E43. The examination of an incisor tooth by the University of Copenhagen showed similar results. However, bacteria of the same species are not necessarily equally toxic. C. bot Alaska E43 has ten genes associated with toxicity, including the critical one, BoNT, which codes for the C. bot toxin. In Neruda’s remains, just one of those ten, BotR, was detected. BoNT was not detected. BotR has a role in activating BoNT to produce botulinum toxin but does not produce toxin itself. However, only 1/3 of the genome (the bacteria’s total DNA code, of which genes are part) was reconstructed, so it is possible that BoNT and other toxic genes were present but not detected.

or not present

Neruda’s medical dossiers document that Neruda had recurrent urinary infections. The DNA analyses showed evidence of bacteria known to cause urinary tract infections.

This section is a reply to a specific request of the magistrate, not summary. Evidence above is a longer treatise on the subject.

III. Weight of evidence of the DNA results

It is impossible to calculate a likelihood ratio that expresses the weight of the microbial evidence under the two hypotheses that Neruda’s death was due to (1) the intervention of third parties versus (2) natural causes of death due to illness because the evidential weight of the microbial evidence cannot be quantified.

IV. Circumstantial support

Neruda died shortly after the military coup in 1973. According to a judgment rendered by a Chilean court in 2021, Pinochet’s henchmen in 1981 poisoned prisoners in the former Chilean Public Prison by botulism, which supports the possibility that they also did so to Neruda in 1973. Unfortunately, there is probably no possibility of comparing the DNA of the 1981 C. bot strains with those found in Neruda’s teeth. If there were and the two were nearly identical, that would give comforting clarity.

Charles Brenner, PhD DNA·VIEW USA	Professor Hendrik Poinar, MSc, PhD McMaster University Canada
Marie-Louise Kampmann, MSc, PhD University of Copenhagen Denmark	Debi Poinar, MSc*) McMaster University Canada
Professor Niels Morling, MD, DMSc University of Copenhagen Denmark	*) Corresponding author (D. Poinar): E-mail address: poinard@mcmaster.ca

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