How is the drug acid smoked?

In the acid bath

Herr Vermeij, what's the best way to make a corpse disappear?

There is no general answer to this. If there were the perfect crime, we wouldn't know anything about it anyway, precisely because it doesn't come out. But in the twenty years here at the institute I have seen a few cases in which the murderers have come up with incredible things.

What do you remember most?

Fifteen years ago someone here in Holland put a corpse together with branches in a wood chipper and then simply spread the mixture over a field. In 2005, someone else chopped up his victim, deep-fried and then thrown the individual parts into a canal, at a distance of many meters from each other.

Pretty scary.

Yes. And one of the longest crime scenes in history, it stretched for many kilometers.

What everyone wonders about the series Breaking Bad has seen: Can a human body really be eliminated without a trace by dissolving it in acid?

Theoretically yes, if enough time and acid is available. A person weighing 80 kilograms consists of around 40 kilograms of water, 24 kilograms of fat, 12 kilograms of proteins and 4 kilograms of bones - all of which is soluble. The situation is different with dentures and gallstones, not to mention metal implants.

What if the killer doesn't leave telltale gold teeth behind?

In two cases we were able to convict the perpetrators. The first was twelve years ago, when I was called to the house of a drug dealer who, according to a witness statement, killed and burned his business partner. But there was nothing to be seen of a stove, but the police found a gray plastic bag in his garden with a five-kilogram block made of a white-gray mass. We thought of heroin or something at first, but it actually turned out to be a cast.

Burying plaster of paris in the garden is unusual, but not punishable ...

... if there are pink and brown dots in it, maybe. In any case, I cast a piece of the compound in epoxy resin, polished it and placed it under our scanning electron microscope. Strange, honeycomb-like structures with thin walls emerged. We then turned up the electron beam properly. Each chemical element in the sample then emits characteristic X-rays. This is how we found out that these structures are made up of calcium, phosphorus and fluorine.

The components of human bones.

That's true for calcium and phosphorus, so the alarm bells were ringing. But fluorine? This is in the toothpaste, but only in traces in the body. No, we suspected that the corpse was dissolved in hydrofluoric acid, because it consists of fluorine and hydrogen. In addition, the suspect was a professional welder and hydrofluoric acid is used in metalworking.

Was this evidence enough for a conviction?

Not at first, especially since I had found in my own experiments that hydrofluoric acid alone is not strong enough to completely dissolve fat and proteins in the human body. This requires hydrolysis: the ions in an acidic solution serve as catalysts to break down the long molecular chains of fats and proteins. These fragments can then combine with water to form fatty or amino acids. However, the fluorine and hydrogen ions in hydrofluoric acid alone are too weak to break the chains.

The situation is different if a mixture of hydrofluoric acid and nitric acid is used. It is used to pickle metals, so it was also available to our suspect. In experiments we first burned human bones and then treated them with this solution. The electron microscope showed exactly the same thin wall structures that we had found in the suspect's plaster block. That result actually earned him an 18-year prison sentence.

Do you have any idea how these tell-tale wall structures might have come about?

They are probably the result of the complex processes that take place when a human body is dissolved. In the case of fats and proteins, as I said, the acid only serves as a catalyst. When the bones decompose, however, it is actually consumed in a chemical reaction. Also, body parts and acid are not easy to mix at the beginning. In areas with a high water content, the fat also clumps together in one place. We believe that the thin wall structures are formed when the bone is hollowed out by the acid not only from the outside, but also via the internal channels and pores. A local excess of fat could then protect the remaining thin walls from further dissolution.

So these characteristic traces could be avoided if the perpetrator stirred the acid bath well?

Constant stirring would actually be very important for him. We believe, however, that these microscopic traces can never be completely avoided. And they are indeed universal, we were also able to detect them in another acid murder recently.

Were the body parts burned beforehand?

No, that's why this second case is so valuable to us. He has shown that the additional cremation of the corpse during the first acid murder had nothing to do with the formation of the thin wall structures. In the second case, we were able to detect the structures in material from drainpipes from a house in Belgium. Here the perpetrators had really tried - by the way, a mother with her sons, also from the drug milieu. They left their two victims in the acid bath for weeks, stirred regularly, skimmed off fat and treated solid components in separate vessels with acid. It was of no use to them, the main perpetrators were sentenced to 15 and 13 years in prison, respectively.

How did the matter come to light?

The horror of the removal of corpses haunted one of the perpetrators so much that he couldn't stand it anymore and went to the police. We already knew what to look for. We are now preparing a technical publication on the two cases in order to point out the tell-tale microstructures to colleagues.

We came across the scientific work of forensic scientist Erwin Vermeij during the production of our feature about the murder of the Russian dissident Alexander Litvinenko. In this case, it wasn't the corpse that was supposed to dissolve, but the murder weapon, the radioactive poison polonium-210. Ultimately, however, it was precisely the short half-life of the rare element that put the investigators on the trail of the perpetrators.

Questions or Criticism? You're welcome!