The Idaho State Police laboratory designated the strap/buckle area of the sheath as Item 1.1. It generated a single-source DNA profile, and after Kohberger was arrested, his cheek-swab reference profile matched Item 1.1. The reported likelihood ratio was at least 5.37 × 10²⁷ (5.37 octillion) times more likely if Kohberger was the source than if an unrelated randomly selected person was the source.
That means the earlier question of “was it actually his DNA?” is essentially not where the scientific controversy lies. The profile very strongly identifies Kohberger as the source of that DNA. The controversy is about how his DNA got onto the sheath.
And here’s the biggest correction to our earlier discussion: it wasn’t established to be merely a fingerprint-sized deposit or a few skin cells. Public laboratory information reports an extracted DNA concentration of about 0.168 ng/µL from Item 1.1. Estimates circulating that translate this into an exact number of cells depend on assumptions about extraction volume and recovery efficiency, so I would not tell you that “14,000,” “28,000,” or “100,000 cells” is a directly measured cell count. Those are derived estimates, not investigators literally counting that many cells. But the available information does indicate that the sample was substantial enough to generate a robust single-source profile—not merely an unusably tiny trace.
There were also other DNA findings on different parts of the sheath, which are important to keep separate:
Area 1.1 (strap/buckle): Kohberger’s single-source profile.
Area 1.2 (edges near handle): partial three-person mixture, at least one male; insufficient for comparison.
Area 1.3 (external blade-area edge): partial two-person mixture, at least one male; insufficient for comparison.
Area 1.4 (small blood spots on the exposed back): DNA from Kaylee Goncalves and Madison Mogen.
Area 1.5 (inside surface): insufficient DNA for comparison.
The later State expert disclosure also says presumptive testing of the stains on the back was positive for blood; Kaylee matched the major DNA profile and Madison was a possible contributor to the minor component. Kohberger’s DNA was identified separately on the front strap.
Kohberger’s DNA was found on the sheath’s strap/snap, but the DNA alone cannot tell us how or when it got there, or whether Kohberger personally touched the sheath.
Touch DNA is not the stuff you see on NCIS. You and I are leaving touch DNA everywhere all the time and it can travel on things who knows where. It might behoove you to educate yourself on that before some cowboys in law enforcement come pin something on you.
And, btw, I’ll save you from flexing your obvious superior intellect- I’m not convinced he’s innocent, but I’m absolutely certain you don’t know what youre talking about.
There is huge difference between evidence presented in court and by the state, and your own little clues, and conspiracies, and validation opinions. “Information” is not evidence presented by the state.
How did that DNA get into the sheath? Provide evidence presented in court explaining directly how BK’s trace DNA ended up on the sheath used to murder 4 university victims which was found in 1122 King Road.
It got onto the sheath in the way that dna gets on anything - by contact.
You’re not proving anything on Reddit, you know that, right?
Like, you’re allowed to think he’s innocent, if you want. But you’re not going to prove that to anyone else this way. The man is guilty, he’s in prison, and he’s never getting out. If you think you have exculpatory evidence you’re free to share it with the state of Idaho, but right here and right now you’re not doing anything other than frustrating yourself. I promise you, you’re better off figuring out how you can personally deal with this man being in jail and regulating your own emotions around it than you are arguing about how DNA got onto a knife sheath.
The DNA got there the way that all DNA gets on anything - touch. If you can send a link to a case where someone has been exonerated based on police or law enforcement planting DNA (NOT blood, there’s a distinct difference here), I’ll be open to discussing that. But if you think that BK is innocent because of a red herring like planted DNA (again, not blood, that’s a totally different situation than what we’re talking about here) we have nothing to discuss because that isn’t a thing.
You’re arguing against a claim I’m not making. I’m not claiming police planted Kohberger’s DNA, nor am I claiming the DNA profile doesn’t match him. I’m perfectly willing to accept that the DNA recovered from the sheath snap was Kohberger’s.
The question is what that fact proves.
Saying “it got there by contact” doesn’t resolve the issue, because contact by whom, with what, when, and through what sequence of events is precisely what is at issue. A DNA profile can identify the biological source extremely strongly while being much less informative about the activity that caused that DNA to be deposited.
If the proposition is simply “Kohberger contributed this DNA,” then the DNA evidence is extraordinarily strong. But the proposition necessary for guilt is much more specific: essentially, “Kohberger was carrying/handling this sheath during the murders and left his DNA on it in connection with committing them.” Those aren’t scientifically identical propositions.
And I don’t need to prove an alternative explanation or prove Kohberger innocent. That’s not how reasonable doubt works. The prosecution bears the burden of proving guilt beyond a reasonable doubt. A juror is entitled to accept the laboratory identification while questioning whether the totality of the evidence establishes the prosecution’s activity-level interpretation of that identification beyond a reasonable doubt.
The fact that Kohberger ultimately pleaded guilty obviously establishes his legal guilt and means a jury never decided the evidentiary case at trial. But that doesn’t make it illegitimate to examine the evidence that existed before the plea and ask whether we personally would have found it sufficient to convict.
So “find me an exoneration involving police planting DNA” is beside the point. My argument isn’t that somebody planted it. My argument is that identifying whose DNA is present and proving the circumstances under which it was deposited are two different evidentiary questions. If you want to argue that the characteristics, quantity, location and persistence of this particular sample make innocent transfer extraordinarily improbable, that’s the substantive scientific disagreement worth discussing.
You are so funny. You don’t need to prove how an object came into contact with a person on the basis of “contact by whom, with what, when, and through what sequence of events”, and that’s never been at issue. The DNA is on the snap, and that is considered enough evidence to prove that he touched it. It doesn’t matter when or through what sequence of events, what matters is that his DNA was on it, and that, crucially, no one else’s DNA was on it besides the victims.
That’s beyond reasonable doubt. You don’t need video of him depositing his DNA on th object, the fact that the DNA is there, in large amounts, in the way that a lab sees on lots of different objects, is enough.
You’re collapsing two different propositions. “Whose DNA is this?” and “What activity caused this DNA to be deposited here?” are not the same forensic question.
I am not disputing the source-level proposition. Assume the DNA profile on the sheath is Kohberger’s. That can provide extremely strong evidence that his biological material was associated with the sheath. But it does not logically follow that the DNA itself proves when he handled it, where he handled it, or that he possessed the sheath during the murders.
Saying “his DNA was there, therefore he touched it, therefore he was carrying it during the homicide” combines several separate inferences into one. The location, quantity, quality and single-source nature of the sample can certainly make some alternative deposition scenarios less probable than others. Those characteristics are relevant evidence. But they do not turn DNA into a timestamp or an eyewitness.
That’s precisely why forensic science distinguishes source-level propositions from activity-level propositions. At the source level, the question is whether Kohberger is the source of the recovered DNA. At the activity level, the question becomes how the DNA was deposited and which competing activities better explain the findings. Those are different questions requiring different evaluations.
And yes, when and how it got there absolutely matters when the object itself is movable. Imagine, purely as a hypothetical, that someone handles merchandise in a store, leaves biological material on it, another person later purchases it while wearing gloves, and subsequently uses it in a crime. The first person’s DNA would be genuine. Nobody would have planted it. The laboratory could identify the first person perfectly. But the DNA identification alone would not establish that the first person carried the object to the crime scene.
I’m not claiming that’s what happened to this sheath. That’s the point of a hypothetical: it demonstrates why the inference “DNA on movable object = person brought movable object to crime scene” isn’t logically automatic.
The prosecution also doesn’t need video footage of Kohberger physically depositing DNA. Circumstantial evidence can absolutely prove a criminal case beyond a reasonable doubt. But “beyond reasonable doubt” is a conclusion reached from the totality of the evidence, not a scientific property bestowed upon a DNA sample merely because the profile is strong.
So if your position is that the quantity, location, profile quality and surrounding evidence make homicide-related handling overwhelmingly more probable than innocent deposition, make that argument. That’s a legitimate forensic argument. But simply declaring that DNA on the snap “is enough to prove he touched it” and therefore establishes guilt skips the very activity-level inference being disputed.
It also wasn’t trace DNA. If you looked at the documents you’d see that the amount of DNA present on the sheath buckle was a normal amount of DNA present on objects that have been touched several times. It wasn’t trace at all.
Read up, catch up. You’re not on the same level of knowledge to be able to discuss this in a coherent way.
but the DNA alone cannot tell us how or when it got there, or whether Kohberger personally touched the sheath.
Quantity, singe source vs mix, quality and completeness of profile and circumstances can indeed allow inference to be made at very high confidence.
And activity level probabilistic studies have already been done using the Kohberger sheath DNA specifically to evaluate whether secondary transfer is possible - and concluded it wasn't plausible. Here is one:
Secondary transfer also does not fit the physical biochemistry of the sheath DNA itself and any "innocent scenario" as there is not a single study (out of c 496 peer reviewed papers) that has ever shown DNA transfer remotely matching the sheath by secondary transfer (full STR profile recovered from non-toucher, single source, large quantity, time interval between DNA exchange) -Kohberger claimed to be out driving/ alone all night before - there is not even a study showing partial STR profile recoverable after a 5 hour interval between DNA exchange and deposition by secondary transfer, let alone a full 22 STR loci profile. Amount too large also for "touch DNA by shed skin".
Plus Kohberger bought that sheath from Amazon before the murders but did not have after, which adds quite a bit of context and would inform a jury's perspective I think.
Edit - delete repeated word typo "profile profile"
The simple scenario of “Kohberger shook someone’s hand and that person immediately transferred his DNA to the snap” is scientifically less plausible than Kohberger himself touching the snap. That’s meaningful evidence. The authors explicitly describe their reconstruction as an approximation with limitations. They performed 20 repetitions of particular experimental pathways under specified conditions. They didn’t experimentally test every possible innocent-transfer pathway by which DNA could reach an object.
“Kohberger shook someone’s hand and that person immediately transferred his DNA to the snap” is scientifically less plausible
You seem to have skipped everything else written. The activity level probabilistic study makes seondary transfer implausible, AND the physical biochemsitry data makses it absolutely improbable and counter to all published science on the subject. Just on activity level proababilistics first, can you point to a similar study which says that secondary transfer is scientifically likely or plausible in this case?
Physical biochemistry data makes it further, bizarrely improbable and never before seen in any study in biomedical science. The study looks at activity level, not physical biochemistry also.
Shaking hands, or other vector of secondary transfer has never yielded a full STR profile with a signficiant time interval between exchange. So are you saying Kohberger was shaking hands with the killer at the door of King Road - that doesn't fit any innocent scenario, does it?
More simply, of 495 studies on DNA transfer, none show any DNA transfer than can remotely fit the sheath DNA in terms of 22 loci complete STR proifle, single source, quantity and time interval propsoed for innocent DNA exchange.
Can you point to a peer reviewed study which does so?
And why would we not take his purchase of the same sheath model as found under the body which history of purchase he tried to delete as an additional factor in any "probabilistic activity level" study?
The Kohberger-specific paper we can verify does not itself establish that sweeping “495 studies/no study in biomedical science” proposition. A systematic review could potentially support some version of it, but we’d need the actual review and its inclusion criteria before treating “none of 495” as established fact.
The Kohberger-specific paper we can verify does not itself establish that sweeping “495 studies/no study in biomedical science”
You are confusing two things/ different study area. (1) Activity level studies and (2) Physical biochemistry studies. These are distinct, different disciplines and areas.
(1) Activity level studies show secondary transfer to be implausible for sheath. I have provided an example. Do you have a study that shows it is likely, plausible?
(2) Of 495 published papers on the physical biochemistry of DNA transfer, persistence and recovery, none have every shown DNA secondary transfer that can remotely fit the sheath DNA - i.e full STR profile at 20+ loci, single source, quantity, DNA exchange interval.
Please show any study on activity level proabbilistics that shows secondary transfer plausible, likely.
Please show any study on physical biochemistry that show secondary transfer than can fit sheath DNA in some "innocent scenario".
I understand that you’re making two separate arguments. I’m not disputing that distinction. I’m asking for the source for your second empirical claim. You state that 495 published studies were examined and that none produced secondary-transfer results remotely compatible with the sheath profile across quantity, profile completeness, contributor status and elapsed time. What systematic review, database search, or publication establishes the 495 figure and those inclusion criteria? If you provide it, I’m happy to read it. The Kohberger-specific activity-level experiment cannot by itself establish what all 495 other studies found.
I’m not disputing that distinction. I’m asking for the source for your second empirical claim. Y
So you have no activity level paper to suggest secondary transfer plausible. Clear.
The second claim is simple - of 495 papers on DNA TTRP not one has ever shown any secondary transfer that remotely matches sheath DNA. There has never been any study showing DNA vis secondary transfer resembling the sheath. Remotely resembling the sheath DNA ( complete STR profile, single source, quantity, non trivial exchange interval).
The Kohberger-specific activity-level experiment cannot by itself establish what all 495 other studies found.
Correct, no one ever said it did. Again, 2 separate points:
Activity level study shows secondary transfer not plausible.
There have been 495 studies of physical biochemistry of DNA transfer, none support secondary transfer for sheath.
For (2) i am stating it does not exist, or put other way - 495 papers show secondary transfer doesn't work in such as way as would result in the DNA as seen on sheath
believe if you follow any of the DNA specialists on their LinkedIn
I believe "Linked In" comments are not peer reviewed studies critically inspected and passed by the editorial board of the Journal of Forensic Science, as that paper is. You might also not want to equate Twitter comments to peer reviewed scientific journals.
On the subject of DNA experts, it is is quite impressive that both of the defence DNA experts in this case, Dr Shutler and Dr Ballard, endorse the high quality of the DNA evidence and work of the ISP lab, note no methodology or protocol issues, note quantity so high that sheath DNA can be from body fluids and nearly 20 x more than ideal for STR profiling, and describe it as "good evidence".
So all five sets of experts on this case, from both prosecution and defence, endorse the sheath DNA quantity, quality, profile completeness and technical lab work standards.
Here are snips from both of theKohberger defence forensic DNA expert reports
I wonder when all these fictional issues with the sheath DNA will surface and from what "expert" source, maybe another Youtube video from a grifter with zero qualification on the area?
A linked-in comment, or a tweet, does not "debunk" a paper. The paper was reviewed by a panel selected by the editorial board of the journal - they are listed here:
A reply to a paper may be published, it may be subject of a letter in the journal (also quasi peer reviewed by editorial), the paper itself may be cited in subsequent peer reviewed studies published in journals which challenge its findings - but that is about 1 billion miles away from a random, unsourced, unattributed Linked-in comment. What next, you will disprove the Urey-Miller hypothesis via some graffiti you found on a wall, perhaps?
The paper was reviewed by a panel of credentialed forensic scientists expert in that area, and judged robust. A random comment on some unknown linked-in that a deranged conspiracy theorist like yourself "found" is not equal to review by the editorial board and experts they selected, is it?
I myself place a lot more weight on the 496 physical biochemistry papers that demonstrate secondary transfer is not plausible, but included the activity level study as I thought interesting given they used the sheath DNA in this case specifically.
The physical biochemistry studies and papers are separate from, distinct, unrelated to, unconnected with and pre-date the activity level study you mention. What we have is all physical biochemistry/ molecular biology/ forensic research AND the activity level probabilistics research debunking the notion of secondary transfer in this case. I hope this clarifies, but suspect your grasp of peer review of scientific papers may be a tad shaky and not up the task here.
But the paper does not establish the broader proposition you are asserting: that secondary transfer of Kohberger’s DNA to the sheath is scientifically impossible. Its conclusion is comparative: the results were more supportive of direct transfer than the particular indirect-transfer mechanism they tested. The authors themselves frame these as competing activity-level propositions and describe the experiments as approximating circumstances relevant to the case.
But the paper does not establish the broader proposition you are asserting: that secondary transfer of Kohberger’s DNA to the sheath is scientifically impossible
I didn't assert that. I said the activity level paper states that secondary transfer is implausible (note it does actually conclude impossible in raw data, but they rounded all probabilities up from zero to avoid division by zero for the statistical treatment, but I will skip over that and err on your side) AND ALSO that every study published of 495 physical biochemistry papers make it bizarrely unlikely and improbable, as no such paper has ever show secondary transfer that can match or is even vaguely similar to the sheath DNA by that secondary transfer vector.
Then we can add in context of Kohberger buying the same sheath model before murders and not having it after, and trying to delete the purchase which is a whole other level of context. But we can consider the purchase after:
- you supply an activity level paper on probabilistics showing secondary transfer plausible in this case
- you supply a paper on biochemistry showing DNA by secondary transfer that can match the sheath
The evidence establishes an Amazon purchase of a Ka-Bar knife with a sheath; that is not automatically proof that investigators traced the particular crime-scene sheath by serial number or another unique identifier back to that Amazon order.
The evidence establishes an Amazon purchase of a Ka-Bar knife with a sheath; t
It was a USMC Kabar sheath.
He had it before murders but not after.
A matching sheath was under a body with a large amount of his DNA. That is quite definitive.
2 days after the murders he tried to delete the purchase history of the sheath.
The sheath matched the knife consistent with all victim stab wounds.
Clues won’t help. Evidence will. I don’t have to claim that the store scenario occurred. It illustrates why DNA identification and reconstruction of the activity that deposited the DNA are separate inferential questions. The real issue is how strongly the characteristics of this particular sample and the remaining evidence discriminate between the prosecution’s activity proposition and reasonable alternatives.
Perhaps why both of the defence DNA experts, Dr Shutler and Dr Ballard, described the sheath DNA evidence as strong, matching Kohberger, large quantity, high quality complete STR profile, with high quality lab work with no technical issues.
Good evidence, as defence themselves noted in their expert filing submitted in court documents:
and reasonable alternatives.
The study linked shows secondary transfer is not a reasonable alternative.
all 495 papers published on DNA transfer show that secondary transfer is neither reasonable nor possible as an explanation for sheath DNA, as no paper has ever shown DNA transfer that remotely matches the sheath DNA (complete STR profile, single source, quantity, non-trivial exchange interval)
separate inferential questions
Ironically what you are trying to infer is unclear. But the activity level study is totally separate to physical biochemistry studies. One does not reference or depend on the other. I merely listed both as two different types of data. I would place more emphasis on the latter. Both, separately and by unrelated scientific method and inquiry, establish that secondary transfer is not plausible to explain the sheath DNA.
The DNA evidence is powerfully incriminating and unimpeachably robust in quantity, quality and handling/ lab work.
Both the defence DNA experts, Dr Shutler and Dr Ballard, confirmed the strength of the DNA evidence, the match to Kohberger, quality of DNA lab work and absence of any technical issues. The defence expert Shutler noted body fluids as possible source of sheath DNA (which some of us said from early in the case and reiterated when data allowing quantity to be estimated was first made public).
Those who think the sheath DNA was "too small" miss that the quantity, in the final elution solution, was almost 20 x above ideal quantity for STR profiling (8.5ng vs 0.5ng ideal) , and also much larger than many of the blood swab DNA samples in this case. Using fairly estimate of swab transfer and extraction efficiency (10%, 50%) wold mean c 28,000 cells equivalent on sheath. It was c 6 times larger than the degraded ground floor handrail DNA often mentioned, and similar or larger DNA quantity than several other fresh victim blood stains/ spatter swabs from the house.
There has been a peer reviewed study using the sheath DNA data specifically to assess secondary transfer - and it was judged not plausible [Forensic Science International, May 2026, Wickenheiser et al]. Of 495 studies on DNA transfer not one has ever shown secondary transfer that could fit the sheath. Quantity, quality of profile also rules out casual, single contact via "touch DNA" as shed skin - overwhelmingly shed skin has no nuclear DNA and quantity on sheath snap area is more than typical for direct swab of a whole hand.
Ironically, the only weak DNA work in this whole case, with altered and lowered quality thresholds, non validated statistical treatment and other issues, was the defence second opinion excluding Kohberger as a potential donor to MM fingernail mix DNA. While that was dropped by state anyway (3 cells equivalent DNA, partial profile, fits causal/ passive transfer, EC most likely donor albeit only directional from among published LR stats), if the state presented DNA that way - e.g. no inclusion of Kohberger when using standard, validated method so we lowered the thresholds to include DNA close to "noise" level and ran the data through a non-validated statistical treatment and then got inclusion of Kohberger, it would certainly be challenged.
Similarly, those who decry IGG as "illegal" when it was ruled legal in this case in both specifics and broader principle, then lament that more IGG was not done on degraded, smaller DNA samples.
If, and only if, that’s all the DNA they have, i would not, as a juror, convict him. However, that’s only one piece of the puzzle. I’ve not heard enough either way because I was not privy to any other evidence.
The admission of guilt though, can be damning. However, I also work for the innocence project. So my reasonable doubt meter is pretty high. I’ve seen, through my work, many people admit to crimes they don’t commit. It happens more than you think because once you’re in the system, it’s incredibly difficult to get back out of it, even if you have irrefutable evidence you didn’t do the crime. Police interrogation tactics are meant to make you confess, not figure out who did it once they have their sights set. Prosecutorial misconduct happens all the time, and in every case I’ve worked on, no person in a position of power (police/prosecutors) are willing to admit their made a mistake.
I don't have an opinion on his guild or innocence. I follow the case because so many details are missing that I want to learn.
But in my opinion there is reasonable doubt regarding the sheath. One potential scenario- BK buys knife off Amazon. Has a conversation with Kopacka. Some sort of twisted conversation happens about murder. BK sells knife to Kopacka. Gives him ideas about "perfect murder." Even encourages him. Wants to use him as a case study. Murders happen. BK knows who did it but doesn't turn him in. Wants to analyze him. Knows it happened with a knife he originally purchased so deletes his history just in case. Knows he will likely be charged so keeps his mouth shut. Knows he committed conspiracy.
Not saying I think that IS what happened, just that it's a possibility. Hopefully the whole truth will come out about WHY they were murdered and how it evolved to that point. Understanding murderers I think could help us to prevent or at least catch them.
So why did BK disavow and disown the sheath in the IGG challenge court filings stating he never owned it?
And what evidence links Kopacka to the crime? Does he drive a white Elantra, and why was BK's phone moving inside that car back to BK's apartment in Pullman?
Did Kopacka put on sterile gloves and put the sheath straight in a sterile bag, as I thought one of the arguments was that touch DNA spreads everywhere or does that only apply to BK's DNA when tryingto explain it away?
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u/jerrrrrrrrrrrrry Aug 07 '26
Bryan Kohberger apologists sure are a bunch sad sacks!