Iowa Forensics Opts For A CSI Style Hack To Save Their Budget


There’s a very effective way of lifting dusty fingerprints from the field, or in a lab. It’s called an Electrostatic Dust Print Lifter — but as you can imagine, it is rather expensive from a forensic supply store. [Bradley VanZee] — from the Iowa Division for International Association for Identification — realized how simple a tool it was, and made his own for just over $50.

But first, how does it work? Electrostatic print lifting is a non-destructive process where you develop an electrostatic field on a sheet of “lifting film” which attracts the dust particles to stick to the film. It’s capable of recovering impressions from both porous and non-porous surfaces — even ones not visible to the naked eye.

Commercial versions of the tool cost upwards of $600-$800 + lift film. The first hack they realized is that instead of using proprietary lift film, it is just as effective to use car window tint instead! The second hack is even more clever — using a 80,000V tazor, some electrical leads, and some tinfoil you can create your own version of the tool. The aluminum foil acts as a ground, and the object you are inspecting is sandwiched between it and the lifting film. Holding the tazor with one electrode to the foil, you can trace the film using the other electrode at a distance, which induces an electrostatic charge in the film, attracting and capturing the dusty fingerprints. Allow the static to discharge, and store the film in a safe place to be digitized later!

Now obviously this is only really effective for flat objects, but it’s still a brilliant hack — especially to save your budget!

[Thanks John!]

32 thoughts on “Iowa Forensics Opts For A CSI Style Hack To Save Their Budget

  1. 1. That is a stun-gun.
    2. Are you trying to avoid using the trademark “Taser” by intentionally misspelling it?
    3. Pretty clever hack. Now they just need to either automate the electrode movement or replicate the actual device more closely, which I believe just needs one “zap” to capture the entire area at once (I’ve only ever seen it on a TV program, though, so it may work like this one).
    4. It would be a bit cumbersome, but a CRT produces a nice static charge over it’s surface, and old TVs are basically free, nowadays. Just get a nice flat Trinitron, put it face-down over your window tint, and turn it on.

    1. Tazor is the plural of Taser. ;)

      I imagine the process works fine, but I wouldn’t want to have to explain in court how you store a print you lifted using window tint in a pizza box.

  2. I saw them do something like this on CSI: go to a local hardware store & get stuff to lift fingerprints. I called BS when I saw Grissom hook it up to a 6V lantern battery, but now I see they almost had it right had they used a stun gun!

  3. He us relying on test lead wire to stand off 80kv? He is going to be in for a big surprise one of these days.

    You can get suitable HV sources from all sorts of things like ionizers from fans, power supplies from electrostatic precipitating dust filters, and the old sharper image ionic breeze filters. You could also take a CCFL ballast and run it through a cockcroft-walton multiplier to get the necessary voltage. There is no real current demand here, just need to create an electrostatic voltage differential.

  4. I really enjoy this hack, however i have a big problem with it. I primarily work with lawyers currently and have worked with I.C.L.E.F. (Indiana continuing legal education foundation) educating lawyers on technologies. In doing this I’ve learned quite a bit going the other way as well. Reading this I can honestly say that anything gathered with it would be a gift from heaven for any defendant finding out that this thing was used. The technology might be solid but there is no way to calibrate it. Heck even breathalyzer results here in Indiana have been challenged recently several times because the company that does the calibration for the machines did not have the correct certification.

    great little hack, but IMHO worthless for any type of forensics that might ever end up in court for any reasons at all.

    1. What’s to calibrate? The perp’s prints are either there or they aren’t. Using window tint film could be a problem unless it’s from a sealed package and is handled with gloves.

      I assume the lift film is in sealed packages and the people using it handle it with gloves.

      In any case, there wouldn’t be any way a suspect would have handled the film in advance.

    2. It’s not fair to compare this against a breathalyzer, which merely generates a number; and if poorly calibrated, can return invalid results in either direction.

      If this thing fails to lift an existing print, then that’s typically in the defendant’s favor, so no need to challenge it. And if it does lift a clear print, that proves it’s working. What exactly would the defense claim in this case? The device is somehow capable of generating spontaneous human fingerprints? That alone would be incredible. But one that also just happens to match the defendant? And who will also typically have been near enough the place the crime was committed, and at the right time, to have feasibly committed it?

      Even without technical knowledge, it only takes a little common sense to realize this isn’t remotely possible, and that any comparison to breathalyzer (mis)calibration is invalid as well. Not saying that common sense is all that common in the legal system though, and the fact that someone who is responsible for educating lawyers on technologies is claiming something like this certainly doesn’t bode well either.

      1. actually calibration would 100% be needed. While doing work as well for machine shops it is amazing the types of calibration there is. You might be wondering where exactly I’m going with this but stay with me, for measurements on something as precise as fingerprints you would have to do measurements and have a way, documented even, showing that 1/4″ is 1/4″. Just look at any gauge blocks in any machine shop, they use those to calibrate calipers and micrometers, but as well have to be sent out to be calibrated. This is precisely what i’m getting at by calibration, they have would have to be proven over and over again, not just a one off hey we got a hit maybe deal. How else would you be able to show that lifting a print with this one off machine gives correct results and not something that could produce an erroneous result.

        so yes IMHO calibration for any type of legal work especially when it comes to identification and any use of the word forensics is a major issue.

        as for educating lawyers on technology not boding well, nice personal shot there but i believe that my point is a very valid one and i was using my past and current experiences with the legal system as point of reference from being in that world where most have not had to be there or get hit with the questions being asked.

        1. This doesn’t really need to make it to court, if they had no idea who committed the crime but managed to get a finger print of someone in the system they can start there and build other evidence ready for court.

          Also, don’t they dust prints anymore over there?

          1. Except that if the defense can get this particular method thrown out, they can then ask the judge to throw out any evidence gained from that lead. It doesn’t happen every time, like on TV, but it does happen.

            I’ve worked as an evidence technician in the past, and one of my best friends is a crime scene investigator. As long as the method is well documented, the prints are clear, and the tech or investigator is experienced and has a good track record, there’s little chance of it being successfully challenged in court. Whenever I had to take the stand in the past, the defense would ask me boilerplate questions about chain of evidence, how my evidence was stored, who had access, etc. I gave truthful, short answers and sounded like I knew what I was doing, and they were done with me in less than five minutes and moved on.

        2. Ok, let’s roll with that, making a big assumption – that the size of the print is changed slightly by the process.

          Is this relevant? I’d say no. A slight size difference is irrelevant compared to the geometric and ratiometric relationships of fingerprint features. It has to be so. I can use a single finger, make several fingerprints, and make them all slightly different sizes or aspect ratios just by stretching or compressing the skin.

          Is this assumption even true? Again, I’d say no. The dust is moving across a small gap, and a straight line is by nature the optimal path. But if so, then a commercial lifter uses the same process and should also produce a size alteration. This would be documented. So would the required calibration process, or the size variation would be considered acceptable. Does such an issue or calibration actually exist?

          To produce a result that could be reasonably challenged, a lifter would have to generate significant erroneous features. And not just simple errors, like slightly altered size, gaps, smudges, etc. It would have to be something that would fool an analyst. Because fingerprints are rarely perfect or complete to begin with, regardless of the quality of reproduction; so any analysis includes dealing with error.

          You have not shown any specific reason why you believe this DIY version would do that, or otherwise fail to function properly. Only generalized analogies that are easily dismissed upon any real inspection. Sorry for the personal jab, but I think it’s justified to expect higher standards from those involved in the legal system.

        3. This is a method of coarse, 1:1 preservation of subtle dust imprints. ie: tire tracks or a shoe print. The process is well established and the technology used to obtain the desired results is well understood.

          Does the brand of super glue used for cyanoacrylate fuming matter when developing crime scene fingerprints? Do investigators have to use special “CSI super glue” for evidence to hold up in court or dollar store CA work just as well?

          1. I would assume the brand and model of cyanoacrylate would matter. Just look at all the different formulations of LocTite there are, and how they produce different results, from requiring heat to remove, to being able to secure fasteners which have already been installed, etc.

  5. i would be surprised if it would hold up in court because the process is not performed by the standard tools.

    just like in old days you could get away with using an old refrigeration compressor to recover the charge from a refrigeration unit and a 20 pound propane tank used on outdoor cooking units.

    not i think the law sais now you have to use a certified recovery unit and certified recovery tank.

    1. Agreed.

      This is essentially a camera that captures an image of a fingerprint off of a surface. I don’t recall hearing of police needing to use a calibrated camera to collect crime scene photographic evidence.

    2. The old “dust and brush” has CENTURIES of established track record. This does not. In NJ, any new technology, even any new version of an existing technology, must pass a court Fyre Test. They can’t use a new model of laser speed tracker or radar gun without proving the new model meets the standard.

  6. I think that the point The Gambler is trying to make is that the perception of something thrown together to obtain evidence can make a judge or jury dismiss the evidence because of their lack of education in science. If one piece of evidence is thrown out, it can have a domino effect on other evidence. Most of us on this forum look at this and say, “The technology is essentially the same. The evidence is likely real.” At the same time, if I was the defendant, I’d be pointing out how unprofessional it looks and questioning the technology to raise that doubt. It’s a fine line.

    1. That sounds fine and all, but this isn’t a complicated device. “We put dust on the prints. We put this on top. The dust sticks to the film.” There’s nowhere for this to go wrong and still get a print, it’s just not possible.

  7. Might be able to make it even cheaper, easier and possibly a bit safer if they used one of those HV power supplies for those cold cathode lamps, or the EL wire. Not sure if the voltage would be high enough though.
    Great thinking.

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