“There was no indication of cachexia. He was an obese man at the time of death,” Dr. Niels Morling, a Danish scientist who helped lead the analysis, said at the time. “All other circumstances in his last phase of life pointed to some kind of infection.”
But crucially, the researchers also found in one of Mr. Neruda’s molars traces of the bacterium clostridium botulinum. Some strains of that bacterium cause botulism, which can paralyze and kill people, and are among the world’s deadliest toxins, sometimes used in biological weapons.
Still, the 2017 analysis was incomplete, and the scientists said they needed more time to determine whether the bacteria was in his body at the time of death — instead of seeping in later — and whether it had killed him.
In their final report on Wednesday, the scientists concluded the bacterium was in his body when he died, in part by finding small amounts in the ground near where he was buried.
But they could not determine whether it killed him, or even if the strain was a toxic one, in part because they were only able to reconstruct about a third of its genome. Because the DNA was so old, it had degraded.
“Botulinum is the most potent poison there is for humans. And therefore, a mention of a person dying with botulinum bacteria in them is hair-raising. It’s sensational,” said Mr. Brenner, the member of the expert panel. “However, the truth is, some botulinum strains do not produce the toxin, and in this case, there was no clear evidence that was the case.”
Toxic botulinum bacteria in humans is more often the result of eating rotten fish, he said. “We don’t have a lot of murderers, but we do have a lot of deaths from botulism,” he said.
Pascale Bonnefoy and Ana Lankes contributed reporting.