Some of you may recall that I live in the Yucatan Peninsula of Mexico.
I was having a discussion with my neighbor about the 43 missing students of the state of Guerrero. The official position of the government is that the bodies were cremated at the garbage dump. Satellite photos have disputed this. There was no fire of this size. And it would have needed a huge fire to accomplish this.
Since no bodies have been recovered, my neighbor is suggesting that the bodies were consumed in an acid bath.
If the acid bath was recovered, would there be any traces of DNA? Or would the acid dissolve all traces of DNA?
As long as all the flesh and bones were fully dissolved, any DNA would also be broken up. It would not be as resistant to acid as many other components of a body.
… which leaves the bones but little more. It might be possible to recover some DNA from the long bones if they hadn’t been broken, but how much time and money would be needed and how workable it would be… would be on the ranges of “a lot” and “not much”.
Edit: actually, there could have been clues left: gold fillings. And possibly titanium implants, but it’s questionable: while the oxidizing properties of nitric acid would have initially protected them, the extremely sour properties of same acid would probably have done with them in time.
It’s not a question of the chemical properties of acid. If DNA is well and thoroughly mixed with sufficient quantities of a strong acid, yes, it will be entirely consumed. But that is in practice a difficult thing to achieve, particularly where something as large as a human body is concerned. Generally, unless you execute a process of industrial chemistry level of thoroughness – giant steel vats, powerful mixers, many hours of reaction – there will be significant chunks of remnants that contain DNA that did not come in thorough contact with the acid – where “significant” from the point of view of a DNA molecules does not necessarily imply large enough to be visible to the naked eye. Practically speaking, it is very likely there would be chunks ranging from micrometer to millimeter size at the very least, and most likely centimeter or larger. Needless to say, these would provide ample amounts of DNA for analysis. The trick would, of course, be finding them, since mm chunks of human remains would be very hard to identify in, say, some jungle dump.
Actually, the difficulty is such that I doubt the gangs would have gone through the trouble. I suspect the bodies are dumped is a grave somewhere in the wilderness. It’s always occurred to me, driving though some of the more wild parts of Canada, that if someone went 20 yards off the road at some random spot in the forest and buried bodies, they’d only be found by sheer luck. I imagine in the tropics, where decay happens faster and plant cover grows faster, the difficulty in finding things would be greater.
The other problem is source and disposal. In BB they had a plastic drum barrel and enough acid to almost fill it - for one body. I assume you’d need to at least match the body weight with acid to dissolve a body; so 43 people x 150lb = 6450lb of strong acid. IIRC, that’s 645 gallons of strong acid. I’m hoping if someone acquired that sort of material out of the blue, it would be noticed - not to mention the logistics of handling it and dumping it. Then again, if they did dump it, there should be significant fish kills in the river all the way out to sea… and if so, any evidence of remaining DNA would be washed away too. And I still suspect you’d need more than 1:1 acid to dissolve a body. And if they made a habit of this, typically dissolving inconvenient corpses, there would be plenty of other evidence from other kills.