# Samantha Karner ![[samantha-karner.png|260]] **Samantha Karner** is a **firearm and tool-mark examiner at the ATF Forensic Science Laboratory** (Washington), with ~6.5 years' experience and an instructor at the **National Firearms Examiner Academy**. She performed the firearm/tool-mark examinations **for the State** in this case — and was then called **as the defense's first witness** on **Day 4** to establish the **limits of the discipline**. *(Name spelling — "Karner" — is our best reading of the audio; the defense exhibits were labeled after her, e.g. "Karner 11.")* ## Why she matters Karner is the rare witness who authored the **State's** forensic reports (Exhibit 32; a 47-page case file) yet delivered the **defense's** most important trial-stage testimony. Called by **Michael Burt** after the State rested, she was used to convert the ballistics record from "match" into "**opinion with limits**." ## Day 4 (July 9) — the reliability/inconclusiveness testimony - **She is the ATF examiner who worked the case for the prosecution.** "I am a firearm and toolmark examiner … at the … bureau of alcohol tobacco firearms and explosives" [06:24:23](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23063s); "At the request of the state of Utah, did you conduct certain examinations … I did" [06:24:59](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23099s); author of the report (Exhibit 32) [06:25:41](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23141s). - **The murder bullet is inconclusive.** The bullet-jacket fragment (Item 6A) "could not be identified or excluded … the result of the comparison was **inconclusive**" [07:11:04](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=25864s); it "may or may not have originated from the same … source" [07:14:02](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=26042s). See [[The Inconclusive Bullet]]. - **The casing, by contrast, is a positive ID.** "My conclusion for one of the exhibits identifies the **cartridge case as being fired in the firearm**" [06:31:27](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23487s). See [[The Casing Match and DNA]], [[The Engraved Casings]]. - **The discipline's limits (DOJ uniform language, Exhibit "Karner 11").** She cannot claim **uniqueness**, **individualization**, **infallibility**, a **zero error rate**, or "**reasonable degree of scientific certainty**" [06:30:41](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23441s)–[06:33:32](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=23612s). The **AFTE** "individualization … is **subjective in nature**" and her conclusions are "**of my opinion**" [07:04:29](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=25469s). - **Error rates.** **NAS (2009)** "fundamental problem … lack of a precisely defined process" [07:25:36](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=26736s); **PCAST (2016)** firearms analysis "falls short … of foundational validity" [07:57:23](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=28643s); her **2023 bullet proficiency test had a 20.4% error rate** [08:03:10](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=28990s). The GRC firearm list is "**not all inclusive … just … an investigative tool**" [06:45:34](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=24334s). - **The State's cross (McBride) rehabilitated her.** The lab is **ANAB-accredited** and proficiency-tested; AFTE ran the **PCAST-requested black-box studies**; her conclusions were **verified by a second analyst** [07:51:53](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=28313s); and the method is "**accepted by courts across the country … routinely admitted … peer reviewed**" [08:04:48](https://www.youtube.com/watch?v=89ZKQIHaJpM&t=29088s). **How to read it.** For **probable cause**, the **casing→rifle** identification holds; the **bullet→rifle** link is openly **inconclusive**. The larger value is a clean **trial-stage** record — a **Rule 702 / reasonable-doubt** foundation on the subjectivity and error rates of firearm identification. See [[Insufficiency of the Evidence]], [[Beating Some Charges Losing Others]], [[Gaps in the Investigation]]. ## Her report — Day-4 exhibit (July 9) ![[exhibit 32 dan examination results.png|560]] *The **ATF firearms laboratory report, Plaintiff's Exhibit 32** — the firearm / tool-mark examination Karner authored and testified to: the Exhibit-1 Mauser rifle test-fired operable, the Exhibit-2 cartridge case **identified as fired in that rifle**, and the tool-mark findings on the engraved rounds.* --- **Related:** [[2026-07-09 - Preliminary Hearing Day 4|Day 4 Legal Review]] · [[2026-07-09 - Preliminary Hearing Day 4 Transcript|Day 4 Transcript]] · [[The Inconclusive Bullet]] · [[The Engraved Casings]] · [[The Casing Match and DNA]] · [[The Rifle]] · [[Jennifer Faumuina]] · [[Brian Davis]] · [[People Index]]