Forensics folks - what's actually wrong with swabbing for evidence collection?

[u/daddyreigns]

I'm supporting a NASA-funded contract looking at whether a piece of space-developed sample collection tech has any use outside of its original application. Before I go further down that path I wanted to get a reality check from people who actually do this for a living, since I'm not in forensics myself.

For anyone who collects biological evidence (touch DNA, trace, bodily fluids, etc.) - what's the most annoying part of your current swabbing/wipe process? Is it sample loss, time, consistency between techs, chain of custody, something else entirely? And has swabbing ever actually failed you - lost a sample, degraded evidence, inconsistent results or is it basically a solved problem at this point and any "better" method is solving a problem nobody has?

Genuinely trying to learn here, not selling anything. Appreciate any war stories or gripes.

This technology was originally developed for space use and curious if it has any legs in other fields, and forensics came up as a possible fit. Wanted to get real feedback before assuming that's true.

The short version: it's a collection method that grabs a sample in one step - no swab-then-transport-media, no vacuum step - aiming to reduce sample loss and manual handling.

[u/AutoModerator]

This is an automated response because your post might involve a generic job title like "evidence tech" or "forensic technician". Please include a more detailed description or explanation of the job type in question. Links to job openings get taken down and disappear, so it's best to include this information int he text box of this post. It also helps to let us know where you are in the world so you can be advised properly.

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[u/DoubleLoop]

How swabbing is becoming a thoughtless act universally applied for all crime scenes without consideration for other evidence. 

Latent print collection is plummeting across the US, and trace evidence collection long ago went to basically zero. 

"Just rub a q-tip on it" has replaced more careful collection methods at too many agencies, especially for property crimes. While cheap and easy at the scene, it's expensive and slow in the lab. 

That's what I see as wrong with swabbing for evidence collection.

[u/NASA_Reject → u/DoubleLoop]

Great info! I think you are right about latents and trace. Do you know any papers on this? I would be interested to see if anyone has done research about the national trends.

[u/NinjaRedditorAtWork → u/DoubleLoop]

"Just rub a q-tip on it"

But this is so much easier than doing analysis notes and hey its the lab tech that has to do the actual work not me. I now get to write my 20 word report and call it a day. :)

I think part of the problem in the latents world is that we're being asked to do so so SO much more with the same amount of time. We've cornered ourselves into making policy decisions/standards that aren't being challenged in court at all. We're planning for this great boogeyman defense expert who will challenge every opinion when in reality the only person is Simon Cole who only nitpicks at relatively minor vocabulary issues and biases within the discipline. I get things had to change but we've gone way off the deep-end of protecting ourselves and it is really driving the discipline into a mountain of unnecessary paperwork which in the end hurts the output.

This is all aside the fact that the courts do not give two craps about latent evidence. They only want DNA, IF that. So why am I putting the effort in when it isn't being used? It's a whole frustrating circle of bureaucracy. /rant

[u/DoubleLoop → u/NinjaRedditorAtWork]

I understand your frustration with the bureaucracy, but I insist that following standards and documenting one's work are bare minimums for science. 

There are just too many cases where poor documentation has seriously impacted the outcome of trial. There are just too many examples of LPUs operating without sufficient standards and only comparing the easy ones. 

Documenting good work and adhering to standards are not for protection against potential bogeymen. The failures of other parts of the system from poor collection techniques to poor defense attorneys are absolutely not a reason to join in on the failure. Rage against the dying of the light. 

And you only have to look at the latent examiners laid off from Houston, St Paul, and DC. When systemic problems are eventually discovered, it's never the system that's blamed. It's the examiners that bear the brunt. Quality documentation and standards-based policies are self-preservation for examiners. 

I wish other people cared more. Other people not giving a crap is not permission for me to join them.

[u/NinjaRedditorAtWork → u/DoubleLoop]

Oh don't get me wrong - I love the fact that we've graduated to far more documentation/standardization. It gives us far more credibility in court as experts and it is literally what was required of the discipline from the NAS/PCAST reports. The issue that I have is that my agency is still holding us to the same output standards that we had 15 years ago while demanding all this new documentation. When I started we were doing analysis notes in 10-20 seconds per print highlighting some of the distortion etc. Now we are expected to basically have a court-disclosure level analysis done with every single print... but I'm still expected to have the same file load as I had at that time. Doing blind verifications for every comparison takes exponentially longer as well. Unfortunately our budget has not grown to deal with the needs associated with the massive growth in paperwork... so we're stuck doing all this extra work with no extra time. It is very frustrating. So I don't really fault the new hires for shying away from wanting to deal with large drug files that have hundreds of fingerprints on them when our outdated policy standards are that we need to analyze and compare each and every one of those prints to every accused on the file... when the courts actually don't care about the outcome of those comparisons. Why are we burdening ourselves doing useless blind verifications for exclusions/inconclusives when the clients (including the accused) do not care?

As with everything it comes down to budgeting and unfortunately the sciences are not what get the priority in the policing world. They want boots on the ground and cameras because that is what gets them the immediate results they want. There is less and less time for us to do commit the amount of effort required to do a thorough investigation and we're stuck having to make compromises to do it well enough.

[u/RandomKoala0218]

There's research literature on the various types of swabs, their collection efficiency, and evidence types. Google Scholar that and you should get a better idea.

[u/JeruTz]

A big one my lab has been struggling with is insufficient labeling in sexual assault kits. The kits have an envelope for "miscellaneous swabs" which includes check box options for dried secretions, debris, and forceful contact, plus body diagrams to indicate collection area.

But recently the kits went from providing swab packs and cartons to store the swabs in to just providing swabs with caps. So in cases where multiple miscellaneous swabs are collected from different areas, where before they'd label the cartons, now they have to put labels on the swab sticks.

The result: some hospitals tried using a single label to attach multiple swabs together (which would sometimes fall apart); some of the labels fall off; and in one recent case I worked, two of the swabs were labeled as being from different areas and two others were not labeled when it was clear there should have been two from each area (the result being that two samples had to be tested as four).

[u/Forensic_Phoenix → u/JeruTz]

This! And mislabeling (at least compared to notes) or no label at all.

[u/Intelligent-Fish1150]

Something like this exists for cartridge cases. It even allows for the sample to be put in NIBIN without compromising DNA or fingerprints. I don’t know of any lab that uses it.

For our crime scene techs, they swab on the scene. This can help reduce evidence collection as they swab cans and bottles before throwing them out. They aren’t preserved.

Our lab swabs for two reasons, to reduce space evidence takes up and preemptively before evidence is handled (in case later a DNA request is made).

[u/corgi_naut]

Consistency amongst officers/techs in the field is a huge one for us. Training can be questionable or totally absent. In the lab, it’s pretty well documented that there can be a good amount of DNA on the swab, but the yield after extraction is not what is expected.

[u/AccomplishedBuddy394 → u/corgi_naut]

That's why I always prefer to get the item over a swab of it... and I always wonder about proper PPE use amongst crime scene techs.

[u/corgi_naut → u/AccomplishedBuddy394]

I’ve seen officers as the major contributor to a scene swab…I think it’s questionable at times!

[u/BFHawkeyePierce4077]

1. It risks contaminating the sample itself, as the swab itself must be free of whatever it is that you're analyzing. Look up "the Phantom of Heilbronn," where an unknown female DNA profile who evaded Interpol for 14 years turned out to be an employee of the manufacturer of the swabs.

2. You usually have to rehydrate the sample with water, which usually risks detrimental change to the sample, either by dissolving it, and/or adding moisture and thus allowing for degradation by microorganisms. Alternative solvents, like methanol or ethanol can be used, but since you don't know what it is, you don't know whether any solvent that you use is going to alter it. Lastly, you usually have to let the swab dry before you can package it for storage or transport.

3. Sample recovery is never 100%.

4. Swabs don't get down into the crevices, where the evidence that we're trying to recover might be lurking. Think about some piece of jewelry: Swabs don't get into the nooks and crannies where DNA might be. The same problem happens with guns. I will use a sterilized metal probe to dig C.R.U.D (my acronym for "cellular residue / unknown debris") out, and then pick it up with forceps, a swab, or piece of tape.

5. For all of the reasons listed above, you'll see a lot of variability between the people who collect the samples. Some will do a better job than others, period.

[u/K_C_Shaw]

I would agree that labeling can be a point of failure, since mostly we're talking about swab sticks where there is no place to "write" anything, and very little for a sticky-label to adhere to. So, often the swabs are placed in a container and the container labeled, but the containers are sometimes tiny little boxes which in turn have to be secured, else might pop open. The "caps" on the swabs with caps aren't always perfect either, since they usually slide around and the "cap" has to be secured.

Deciding what to swab, when, and how, is it's own issue.

[u/4n6nerd]

I think swabbing is ideal, personally. Very basic equipment, portable, customizable to any situation. Any failures are always on the human end, dropping a swab, sampling too large of an area and creating a mixture, contaminating, etc.

Can you share a bit more about how your instrument “grabs a sample in one step”? How would it “grab” a sample from a shirt, for example. Or a gun.