European criminal mastermind's DNA turns out to be tainted forensic swab

A cotton swab may be the most wanted criminal in Europe. For years, cops across southeastern Europe have hunted an cop-killing eastern European woman whose DNA turned up at 17 crime scenes. The crimes were wildly diverse, geographically separated, and had no visible pattern.

You see where this is going, right? It's now believed that the DNA was introduced to the forensic swabs at the factory, and that cops have been hunting someone who probably sticks q-tips in baggies all day and has never committed a crime.

It now turns out that the several-hundred-men task force might have really been chasing a phantom. Alarmed by the apparent randomness of the crimes, involving both highly professional work and seemingly amateur break-ins, they started checking for contaminations in the labwork. The likeliest suspect now are the cotton swabs used to collect evidence at the crime scene. All the swabs used in the forensics works were sourced from the same supplier, a company in northern Germany that employs several eastern-European women that would fit the profile. Even more incriminating, the state of Bavaria lies right in the center of the crimes’ locations, without ever finding matching DNA in crimes on its territory. Guess what: they get their cotton swabs from a different supplier.

By the way: contaminated cotton swabs aren”t as trivial to avoid as one might think. It’s relatively easy to sterilize cotton to prevent infections. Forensics however require a complete destruction or removal of any DNA contamination, which is apparently a lot harder.

The Heilbronn DNA Mixup (Thanks, Oliver!)



  1. Wait, how is this worker getting her DNA on *every* cotton swab she processes? Maybe there’s a different crime being committed, here!

  2. #1, who said she’s getting her DNA on every cotton swab she processes? As far as we know, her DNA has only showed up on 17 swabs.

  3. Wouldn’t it be the ultimate if this person both worked at a forensic cotton swab factory AND was a serial killer. They could then intentionally taint the cotton swabs at their job, and despite being a suspect have perfect plausible deniability. It’s genius!

  4. Or maybe the lab worker really did commit all those crimes, knowing her DNA would have a perfect excuse for showing up at the scenes.

  5. This also happened in a number of IRA-related terrorism cases over about a decade in the eighties and nineties. Much later they realized that the centrefuge that they had used to test for explosive residue was tainted (and had been for a long time) and several people’s cases were reviewed and overturned.

  6. Haven’t the police ever heard of control samples? Every high school biology student learns about the ways in which one separates real data from systemic data.

  7. Exactly, Nixiebunny. The first thing that came to my mind was “why weren’t they running controls?”

    Such a simple, stupid mistake.

  8. ‘For years, cops across southeastern Europe have hunted an cop-killing eastern European woman whose DNA turned up at 17 crime scenes. The crimes were wildly diverse, geographically separated, and had no visible pattern.’

    I think Sherlock Holmes would have said that if you eliminate the unlikelihood that a single person commited these crimes, you are left with the inescapable conclusion that the swabs were contaminated, either at the factory or in transit from the factory.

  9. you have to keep in mind what people want from their legal system is peace of mind, not truth.
    The important thing is that someone be convicted. When forensics came along it was adopted because it got more solid results in the form of a body to hang, not because it freed the innocent.

  10. reminds me of the case where a chip fab plant was getting a ridiculous number of rejects and they finally traced it to the stores guy unpacking and individually counting the blank wafers on his dusty bench…

    he wanted to make sure that each carton actually contained what it said it did… didn’t realise that the wafers were only supposed to be unpacked in a clean room…

  11. *SIGH*
    So many comments here regarding whether this supposed Contaminator0 could actually be charged and strung up for any number of byzantine, Kafka-esque crimes as a result of being clumsy in the factory.

    I’m wondering if this because you/we are all love a good “Brazil”-like story or if it’s because this is what we’ve come to expect from the law ?

    For myself I would say “both”.

  12. To make it even more funnier:

    Some of you suggested to work as a killer AND swab factory worker. This seems to be a good choice:

    Some half official organisations like the ‘assosiation of german criminal investigators’, stepped forward and called for a “DNA proof quality seal” for sucht items.
    BUT, since it’s not easy to remove/destroy any DNA from/on the items, they introduced the funny idea to add the DNA code of ANY worker having handled a given batch of products to the delivery papers, so the can IGNORE any occurance of this…

    NO JOKE !

  13. oliver: that should not be a real problem if the send the swaps to differnt regions without notifing the coworkers, sure they could be in the right region. But europe is big, and it would be a mayor crap shoot for the factory worker.

  14. I can imagine the facepalm that went around when they figured this one out.

    All that time, all that money, and all that energy chasing the enigmatic Eastern European killer, just to find out she’s just some mild-mannered drone at the factory, packing the swabs into boxes by day, then going home to her 14 cats and watching television all evening.

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