Commonwealth v. Read — Trial ArchiveTeri Kun
Testimony Impact
Teri Kun is a forensic scientist at UC Davis's veterinary genetics laboratory who specializes in animal DNA analysis. She was called by the prosecution in Trial 1 to report results from testing two swabs taken from a shirt relevant to the case. Her testimony centered on the absence of canine DNA and the presence of pig DNA, whose source she said was undetermined; food was one possible source.
Challenges & Responses
What attorneys challenged during examination and how the witness responded.
Jackson challenged the weight of Kun's findings by establishing that she had no visibility into MSP's swab collection methods, that inhibitors or degradation could mask dog DNA even when present, and that her conclusions were limited to the swabs she received rather than the garment itself. In recross, he attempted to further undermine her by questioning the proficiency testing history of the MSP analyst who collected the swabs, though the judge sustained an objection and that line of questioning was cut off.
Notable Quotes From The Record
“There's no difference. The accreditation is the same.”
Establishes that UC Davis's animal DNA lab meets the same accreditation standards as human DNA crime labs, bolstering the reliability of her findings.
“We did not see any K9 DNA.”
The central finding — no canine DNA detected on the shirt swabs using the K9-specific qPCR test.
“So the only result we got for both those swabs was for the pig.”
Kun testified that pig was the only animal result from the two tested swabs. She could not identify its source and later said food was one possible source.
“Yes, it could be from food. We have tested the meat ID test — in fact, that's what it was developed for, was for testing food products — and so we've seen it come from cooked pork, cooked bacon.”
Kun said pig DNA could come from food and noted the meat-identification test was developed for food products; she did not conclude that food was the source in this case.
“I only have the swabs to test — that's the only thing I can talk about.”
Establishes the narrow scope of Kun's analysis — she tested swabs, not the garment itself.
“I don't know anything about how they took those swabs.”
Highlights the chain of custody gap — Kun had no visibility into MSP's collection methods.
“It could, yes. It's just — you can't see it if it's obscured, and you can't see it if it's degraded.”
Kun concedes that canine DNA could be present but undetectable due to inhibition or degradation.
“No.”
Kun confirms dog claws are not a good source of DNA, supporting defense argument that a dog bite (saliva-based) rather than scratch would be the relevant DNA transfer mechanism.
“I gave her our basic swabbing practice. Even though they are a crime lab, I would assume that they would know what they were doing — which would be to swab with the sterile swab using sterile water, allowing the swab to dry completely, and then packaging in paper and storing at room temperature before sending it to us.”
Addresses chain-of-custody concerns raised on cross by showing UC Davis provided collection guidance to the state lab.
“The mitochondrial DNA is a hardier DNA — there's a lot more of it. When we're testing for nuclear DNA, like I explained before, there's only one copy of DNA in a cell, whereas for the mitochondrial, in a cell there's thousands. So you can have a lot more there. It makes for a better test, at least in terms of species — it's just a more sensitive test.”
Establishes that the test which found no canine DNA was the more sensitive of the two methods, countering the defense's inhibition argument.
“No. The IPC worked very well.”
Confirms the mitochondrial DNA test had no inhibitors, directly rebutting Jackson's cross-examination point that inhibitors could explain the absence of canine DNA.
Key Moments
- Kun testified that both swabs from the shirt tested negative for canine DNA using a K9-specific qPCR test, and that the only animal DNA detected was pig. She said the source of the pig DNA was undetermined; food was one possible source, and the species identification test was developed for testing food products.
- She established that UC Davis's animal DNA laboratory holds the same ANAB accreditation as human DNA crime labs, directly countering any suggestion that animal forensic testing is held to a lower standard than conventional forensic analysis.
- On cross-examination, Jackson drew out that Kun had tested only the swabs — not the source garment itself — and that she had no knowledge of how MSP collected those swabs, establishing a chain of custody gap between the collection and the UC Davis analysis.
- Jackson's most significant cross-examination point reframed Kun's conclusion: he got her to agree that her negative result did not mean there was no dog DNA on the shirt, only that the swabs she received did not yield a positive result — a distinction that left open the possibility of inhibition, degradation, or inadequate collection.
- On redirect, Kun countered the inhibition argument by clarifying that the mitochondrial DNA test — which is more sensitive than the nuclear DNA test due to its higher copy number — also returned negative for canine DNA, and that the internal positive control confirmed the test was free of inhibitors.