Extracting DNA from the air – DNA evidence of human occupancy in indoor premises

https://www.imdb.com/title/tt0119177/ was conservative. Great movie though.

From the abstract:

> Detectable levels of DNA were also observed in air and dust samples from ultra-clean forensic laboratories which can potentially contaminate casework samples.

Great news for criminal defense attorneys.

The defense attorneys of criminal criminal forensics lab technicians at least.

I feel like this is one of those prescient movies like Pleasantville and Idiocracy we should force voters to watch again before voting.

Dexter Morgan wins again.

At work we do this with DNA floating around in the ocean (have to track down all those nasty invasive crabs) but I wouldn’t have guessed we could do this with the air around us as well. That’s so cool.

Maybe we should spin up an air-based version for the office to keep track of who’s in coming to work the most

More like who is sick a lot (sneezing and distributing dna on multiple surfaces in the blast radius)

Yeah, eDNA is exactly what I thought of when I saw this.

How would that argument go? As far as I understand it, the DNA of the occupants of said lab may be found. That would mean that the criminal samples may also contain DNA of the lab occupants/scientists. Isn’t that the case currently as well and those DNA parts would be omitted?

What if the murderer works in the lab?

The Phantom of Heilbronn!

https://en.wikipedia.org/wiki/Phantom_of_Heilbronn

That would ideal, yet we still got things like this:

https://en.wikipedia.org/wiki/Phantom_of_Heilbronn

Woman at a cotton swab factory was identified after being considered a serial killer.

This is a slightly older paper, note that air environmental DNA now has progressed a lot, especially for species mapping.

Here's a cool recent paper showing you can extract DNA of local species from spider webs, by sequencing DNA stuck to spider webs from next to a zoo https://www.sciencedirect.com/science/article/pii/S258900422...

It’s possibly not the GP’s point, but in general the more DNA that is available the better from a defense perspective. Many wrongful convictions involve a lack of physical evidence. Recent advances like “touch dna” and “m-vac” have led to new DNA evidence used in actual innocence decisions. Too often, a jury convicts a likely suspect on weak circumstantial evidence. Just as with Touch DNA, Air DNA will create new problems with avoiding contamination.

The path toward Air DNA has been known for years [0]. Wouldn’t be surprised to learn crime scene investigators have been sampling and storing air in high profile cases ready for the tech to catch up.

[0] https://www.science.org/content/article/dna-pulled-thin-air-...

It cuts both ways, there was this high profile case of the son of a very rich and powerful family brutally murdering his working class girlfriend in his family mansion with some family present, motives still unknown.

In the autopsy they discovered sperm from a 3rd person on her body, tried to claim that it was an infidelity case(you get different sentece depending on your motives and circumstances) but later it was revealed that this was just a contamination during the autopsy.

So, the more forensic options the better but likely longer and more expensive trials. All lawyers win.

Phantom of Heilbronn strikes again: https://en.wikipedia.org/wiki/Phantom_of_Heilbronn

> just a contamination during the autopsy.

How does sperm end up on her body during the autopsy? Are we talking necrophilia or are there multiple murdered bodies laying next to each other and the tools are re-used or something?

Jeff Bezos is probably already throwing millions of dollars at this in case it'll help him punish people for having a toilet break.

So glad someone mentioned that. A great movie I still enjoy today!

IRRC The official explanation is that there were a few autopsies going on at the same time in that facility and it came from the body next to hers. The public opinion was that they bribed the technician to contaminate her body.

The whole case is a huge mess with attempts of cover ups, months long manhunts and all kinds of conspiracy theories. The killer was sentenced to 24 years of prison but unalived himself in prison and there're still conspiracy theories saying that he actually escaped to China because he was studying Chinese in prison prior that. This happened more than 10 years ago and last year they opened his grave to check the remains and again it was confirmed that that's him. Yet, this is still not enough to end the public discussion and conspiracy theories.

Anyway, if anyone is curious this is the case in question: https://en.wikipedia.org/wiki/Murder_of_Münevver_Karabulut

Unfortunately, the juicy literature around that is mostly in Turkish.

You can say he killed himself it’s not kitkots

Fart detector

I have always wondered why DNA is an accepted evidence. It's so easy to contaminate a crime scene or bring someone else hair, skin cells, etc by mistake.

In theory, you could do a "perfect crime" by going to a seedy part of town, picking up a dropped cigarette butt, and leaving it at the crime scene, framing someone else.

In reality, criminals are angry, frightened, in a rush, high or stupid, and they make the most elementary mistakes, so DNA and fingerprints work just fine almost all the time. In like 99% of cases there's not much doubt about who did it, the main thing is to have a watertight case against them when they deny it.

> unalived himself

In English the phrase is “killed himself”.

Because people believe it, and courts have accepted as fact that DNA evidence is infallible. Certainly there have been cases where DNA has been successfully challenged, but those are very rare. In the overwhelming number of cases where DNA evidence is present, it is a self-fulfilling prophecy for juries and judges.

If there is DNA evidence that is almost a guilty verdict. It should be more closely scrutinized but not everyone is rich enough to afford a real defense.

>so DNA and fingerprints work just fine almost all the time.

except for all of those innocent folks that have had their lives ruined by that 'almost all the time' caveat, it's great!

here's a report[0] that says something like 80% + of criminal forensic work has major mistakes within it.

[0]: https://www.criminallegalnews.org/news/2024/may/15/report-fi...

Feel free to use your choice of synonym when you are writing something.

So, DNA shedding basically?

That was interesting story, the ending in hindsight seems obvious. Thank you for sharing.

TIL that the kids actually use it [1], and it's in dictionaries [2] etc so arguably it's actually English.

[1]: https://medium.com/new-writers-welcome/unalive-the-birth-of-...

[2]: https://www.dictionary.com/browse/unalive

Edit: typo.

Quoting from that:

> At 100% of the 130 examinations analyzed, seized drug analysis was the examination with the highest percentage of Type 2 errors. It was followed by pediatric physical abuse (83% of cases had forensic errors with 22% having Type 2 errors out of 60 cases analyzed), fire debris not including chemical analysis (78% of cases/38% Type 2 in 45 cases), bitemark comparison (77% of cases/73% Type 2 in 44), pediatric sexual abuse (72% of cases/34% Type 2 in 64), serology (68% of cases/26% Type 2 in 204), shoe/foot impressions (66% of cases/41% Type 2 in 32), DNA (64% of cases/14% Type 2 in 64), hair comparison (59% of cases/20% Type 2 in 143), and blood spatter (58% of cases/27% Type 2 in 33).

Also this sample comes from cases where people were exonerated, which could cluster around poor quality police work in general. And is US-based where policing is all kinds of messed up.

Reminds me of the case of David Butler.

"Mr Butler has a rare skin condition, which means he sheds flakes of skin, leaving behind much larger traces of DNA than the average person. He worked as a taxi driver, and so it was possible for his DNA to be transferred from his taxi via money or another person, onto the murder victim."

https://www.bbc.com/news/science-environment-19412819

They only say it to avoid word filters on certain algorithm-driven sites. Your comment won't be automatically flagged, demoted, or shadow banned here for using naughty words that corporate advertisers don't like.

Normally I'm more than happy to roll with someone's choice of words - if you want to use "literally" to describe things that are not literal, please, fill your skibidi or whatever, but I'm hostile towards it when it's an attempt to appease a corporation's filters. I get it, you gotta use it where you gotta use it, but I hate the indicators that our language is being filtered everywhere by certain social media's moderation rules.

That's not language changing because of fresh eyes, it's because of tired eyes looking towards the bottom dollar.

It's not about filters, I like using unalive in the context of suicide when I have no sympathy to the person who dies. It's such a nice dehumanizing word.

But it's entered the vernacular because of the filters.

I only mentioned it because it took me a few moments to figure out what you had actually written since I assumed it was a typo or mistranslation. It distracts from what you’ve written.

It sounds kinder and gentler, to me, more like a word you’d use in polite company to avoid speaking crassly about someone respected.

That's true, some day in the future somebody will make 5 seconds long, long format documentary about the fascinating origins of the word :)

It has a passive aggressive character, I like that word a lot.

Surely you can understand that when certain behaviours or phrases become fashionable, they can become detached from the culture that generated them.

HN doesn't filter "suicide" though. This is organic language. Free-range, grass-fed, and GMO-free.

Tiktots?

Yeah, my argument is we shouldn't use "unalive" when we don't have to.

Well, that’s going to make it harder to hide from the hunter-killer bots

When we're talking about quality of evidence, saying "in reality" is skipping to your conclusion. Are smart careful people rare among known criminals? Well, yes. What would you expect to see? https://www.econlib.org/archives/2015/02/the_wittgenstei.htm...

Suicide is a statement, it is the last act of somebody against the society. It is something serious that puts the burden on the shoulders of the remaining. It has long, deep history attached to it.

Unalive on the other hand is a simplistic word that has neither of those, it is originally derived as an attempt to bypass automatic filter. IMHO using it for someone without the practical need to bypass censorship takes away the heft of their act. Makes it insignificant.

This article... keeps repeating phrases about criminals, authorities, safe-houses, solving crimes. Feels off. I was expecting this to focus on the lab techniques, feasibility, technical details. It jumps straight from forensic application details to results without the in-between. I think the in-between is the interesting part.

It's as if they took the token sentence that goes in an abstract about potential applications, and turned it into the meat of the article.

It sounds like they are using standard extraction kits, them analyzing with RT-PCR.

I wouldn't be surprised that some some agencies *cough*Mosad*cough* are gathering DNA of leaders of all countries, and analyzing them, and potentially building bioweapons to target them. It looks like all you need to do is to get the HEPA filter from the room where the target was .

That is the origin of the phrase, but it has since entered colloquial vernacular... as pretty much all terms used on social media do.

Pick any sentence and trace the words back to their origin and you'll find some sort of story about where it was borrowed from. That's just how language works. It isn't anything new -- we're all just older than we've ever been. Every generation coins new terms.

you just did tho

(I am currently reading and infected by Hofstadter's "Surfaces and Essences: Analogy as the Fuel and Fire of Thinking" which I think would side with using unalive, which might also construe a set larger than that of "dead.")

> going to a seedy part of town, picking up a dropped cigarette butt, and leaving it at the crime scene

I've sometimes conjectured collecting hair from barbershops and making a dusting bag that steadily fluffs out hairs to dirty up a crime scene. Maybe get some saliva from grocery store sample spoons.

Interesting. Link or something?

I provided some more details and a link here: https://news.ycombinator.com/item?id=43396911

I haven't seen that, I find it strange.

This sounds very expensive, of uncertain efficacy, and if you use an engineered organism, it will likely be detected if you use modified DNA.

I accept an agency like Mosad or the CIA would attempt it though. CIA tried so many crazy schemes to try to kill or embarrass Castro and failed every time. Mosad loves balls to the walls evil schemes too, like the pagers. It would be one of those situations where they leave a stupid trace and everyone knows it's them and they are untouchable so they don't care and even enjoy the attention.

The word filters must adapt pretty soon. So we'll get new terms.

I'm not against language growth, but the reason this is happening is upsetting to me.

I'm in agreement, but one thought that crossed my mind is how the population in China self-censors and I wonder if this is kind of like that. Rather than tailor the terminology to different environments, the person just chooses the "safe" term all the time.

> I'm hostile towards it when it's an attempt to appease a corporation's filters

Maybe you should be hostile towards the corporations that create those filters instead.

> you could do a "perfect crime" by going to a seedy part of town, picking up a dropped cigarette butt, and leaving it at the crime scene, framing someone else

Framing someone else is not a perfect crime. A perfect crime finds no criminal, accused or convicted.

If you know my mother in law, you don't need a DNA tester to know she's been in the restroom.

Anyone remember the movie Gattaca?

The next gen is semantic and sentiment filters, the age of wordlists is over.

When was the last time you were in China? I'm curious about this self-censoring you're talking about. Did you observe it personally?

And early Europeans avoided saying the name of the terrifying land mammal out of taboo / fear it would summon it, and instead referred to it as either "the brown one" or "wild animal" (exact etymology is unclear which it was), giving us the word "bear", to the point where the "arktos" based word has been lost. Often times euphemisms stick.

https://en.wikipedia.org/wiki/Bear#Etymology

You're wouldn't be the first adult to be unfamiliar with slang. Language spreads socially.

If you're taking the time to write one or more posts about this, you are implicitly against language growth, you've just found a justification for being against it that you find acceptable to your worldview.

Yes, there are occasions where I would take exception to language evolution. If we entered a pattern of 1984-era newspeak I'd take exception there as well. I think it is usually the product of a poorly considered stance for one to be an absolutist about the vast majority things.

Creating reasonable doubt as a backup plan in case your perfect caper isn't as perfect as you believe is just good practice.

Rule 43(a) in the criminal procedures handbook IIRC.

There are 10s if not 100s of articles on it, and even a paper written about it: https://as.nyu.edu/content/dam/nyu-as/politics/documents/The.... One does not have to be in China or observe it personally to know of its existence.

Why not both?

Makes me wonder if dogs can smell your DNA.

Do you think this would become doable by private citizens in the near future for a reasonable amount of money? I've been curious about how far upstream the sculpins are in our local streams. I've seen some in pretty small streams but looking for them typically involves standing still in very cold water for long enough to see them move.

Euphemism is already common, particularly when discussing sensitive topics like the cycle of life, bodily functions, etc. You are probably okay with many existing euphemisms because they are familiar. This really isn't a social media thing, newspaper obituaries also use euphemisms for death. e.g. "passed away", "departed", "eternal rest", etc.

Yes, because that euphemistic language is there to lighten the blow. "unalive" is an attempt to bypass a social media filter and speaks to the shift in how and why words enter our lexicon.

Are you against profanity filters? What's the difference?

Well, because "suicide" isn't profane. It might be considered a pseudo-profanity, but people don't stop saying swearing because of profanity filters. This is an instance where the filter is feeding back into the zeitgeist.

Okay, so from the one you linked:

>Respondents who are the most highly educated, have the highest number of daily posts on social media, and spend the most time on social media, appear to self censor criticisms of the government on social media more than they self censor praise of the government on social media. Other respondents do not appear to self-censor criticism of the government on social media. However, my findings are severely limited by my small sample size.

I was actually asking for accounts of firsthand experience, not ideological slop.

I get the opposite out of it. Using the negative prefix weakens the word, emphasizing what it is not instead of what it is, when act like suicide is not just the state of being not alive. The phrasing isn't committed enough to be oxymoronic and it ends up feeling impersonal and indirect.

But maybe I'm just an old man yelling at a cloud.

I quoted it for specificity. I suppose I could have said "the word formerly known as suicide" but that is probably a phrasing that anyone young enough to unironically use the word formerly known as suicide wouldn't understand.

Yes. I am more upset by the one responsible for the filtering than the effect it's having on the zeitgeist.

I’m not sure! Because the water would move the dna relatively quickly it could be hard to get good results at the higher ends of their range. And I’m not sure about costs, but I’ll look into it.

One strategy that might work, though you’d need to take care and get permission: create a barrier to downstream so sculpins can’t come upstream, and place a trap above the barrier and see if any enter the trap after a few hours. That should tell you if they’re occupying that part of the stream. Just sticks with a mesh net placed as a barrier should be sufficient to prevent any downstream occupants from coming up and entering the trap.

Another would be to place a camera in the water and review the footage. I use this approach with an iPhone 15 Pro (I just stick it straight in the stream) and I get excellent results. There are always really cool animals popping up. Here’s an example: https://youtu.be/N9PLra7amfs?si=kZ01cFZ8upKLxNPb

This was in a very tiny puddle off the side of a creek in summer. At a glance it appeared empty, but after putting the camera in and walking away for 10 minutes or so, all kinds of creatures like this sticklebacks came out of the detritus.

There are some direct-to-consumer companies popping up that do this for you for <$300 per sample. New Zealand has Wilderlab, for example, https://www.wilderlab.co.nz/, the UK has Nature Metrics https://www.naturemetrics.com/

They send you usually a syringe with some filter paper in it, you push water through the filter paper, send the paper back, and they sequence the DNA stuck in the paper and send you a report (and add the sightings to their database).

That seems an especially good reason to distrust DNA evidence using the technique from this paper. It relies on such a small amount of DNA, in dust, that if someone opened a window and a stranger walked by, the interior of a room might be contaminated with the strangers DNA. Also people are mobile, their clothing will pick up DNA dust from one location and shed it in another location. There may already be DNA dust from a million people in any one location. Even if you suck the DNA directly out of the air, you don't know where that air has previously been.

I would be very surprised if anyone other than you sees it that way. The fact you had to explain that distinction shows the uselessness of the word. In fact all you’ve done is draw attention to this guy’s suicide and give it significance.

Given the upvotes, obviously there are more people that are on the same page with me on this than not.

Does seem strange in retrospect that if looking for 'invalids' is so paramount, just install Hoover air curtains everywhere.

Thanks. I guess I was thinking about looking to see if there is dna from upstream passing by. At some point I'd guess it is hard to tell if there are fish upstream but I'm not sure how to think about what factors are important. On the other hand just looking at streams isn't the worst thing to do.

I don't think my own curiosity is a good enough reason to build a trap or barrier. But a camera is a good idea. I actually just picked up some parts from blue robotics to put together a setup for one or more cameras using some stuff I have laying around.

Cool sticklebacks! One of the places I stumbled on Sculpins was in the Taylor River on Vancouver island. I saw something moving and nearly froze myself staying in until I found several of them.

A few years ago i picked up the old (but famous) cases of Brad Cooper and Casey Anthony as they have tons of available digital forensics evidence.

I double-checked the forensics work and found several mistakes in processes, assumptions and technical conclusions. I sent off my findings to people associated with Project Innocence - not because I found anything that proved Cooper or Anthony's innocence, quite the opposite. Instead, I wanted to let them know that forensics experts can make mistakes.

It is interesting that scientific work have fault-finding processes like peer-reviews, but forensics investigations in court cases does not.

Nice, I was very close to that area (maybe 50km over the woods and mountains to the east). There were tons of sculpins in that river, too. Such a beautiful area.

I've never seen blue robotics before. I almost wish I hadn't, haha. This is going to soak up some time.

Their low light USB camera looks awesome for stream monitoring. You could probably even get decent footage in the shady areas (where I find a lot of fish prefer to be). Maybe under some rocks on an overcast day with lots of diffused light? Could be awesome!

Its peak draw is only 220mA so you could actually record a ton of footage on a raspberry pi 5 without a massive power source (10,000mAh should get you somewhere around 2.5 hours, I think?)