---
title: "Law Enforcement Expert Not Allowed to Opine on Stated Reasons for Firing"
meta:
  "og:description": "The law enforcement expert did not use any identifiable methodology to connect his observation to the ultimate conclusion about an imminent threat of death or serious bodily injury"
  "og:title": "Law Enforcement Expert Not Allowed to Opine on Stated Reasons for Firing "
  author: "Shuva Guha Thakurta"
  description: "The law enforcement expert did not use any identifiable methodology to connect his observation to the ultimate conclusion about an imminent threat of death or serious bodily injury"
---

# Law Enforcement Expert Not Allowed to Opine on Stated Reasons for Firing

Posted on August 17, 2026 by Shuva Guha Thakurta

Plaintiff Westley Henson is the father of Joseph Henson (the "Decedent"). On February 23, 2024, Defendant Aram Derderian, a deputy with the Los Angeles County Sheriff's Department, confronted the Decedent outside a gas station. Plaintiff alleged that the Decedent was not armed with a firearm. Plaintiff alleged that Derderian "shot at Decedent multiple times, including shooting after [Decedent] turned to run away." As a result of his injuries, Decedent passed away.

Plaintiff sought to exclude some of the opinions of two of Defendants' experts: (1) [Jeffrey A. Martin](https://expertwitnessprofiler.com/expert-witness/Jeffrey-Martin/1557575), a "human factors" expert, and (2) Dr. [Kris Mohandie](https://expertwitnessprofiler.com/expert-witness/Krishnan-Mohandie/1531360), a psychologist.

![Law Enforcement Expert Not Allowed to Opine on Stated Reasons for Firing ](https://media.jurimatic.com/images/blog_pic_640X4803.webp)

## Law Enforcement Expert Witness

[Jeffrey Alan Martin](https://expertwitnessprofiler.com/expert-witness/Jeffrey-Martin/1557575) is a retired police sergeant from the San Jose, California, Police Department. Martin is a former labor relations attorney whose practice focuses on representing public safety personnel in administrative matters. He also authored "Daily Training Bulletins" on various police practices, including use-of-force, for Lexipol, L.L.C. In that capacity, Martin regularly applied policy, legal, and other police practices concepts to fact patterns to determine whether the presented conduct would likely be deemed within policy.

[Want to know more about the challenges Jeffrey Martin has faced? Get the full details with our Challenge Study report](https://expertwitnessprofiler.com/order/add?eId=1557575&pId=3).

## **Psychology Expert Witness**

[Krishnan Raj Mohandie](https://expertwitnessprofiler.com/expert-witness/Krishnan-Mohandie/1531360) is a California licensed psychologist (PSY12105) trained in clinical, police, and forensic psychology. Mohandie is a Board-Certified Specialist in Police and Public Safety Psychology through the American Board of Professional Psychology.

[Gain a comprehensive understanding of Kris Mohandie’s qualifications and casework history with his Expert Witness Profile report](https://expertwitnessprofiler.com/order/add?eId=1531360&pId=3).

## **Discussion by the Court**

As a threshold matter, Defendants argued that both motions to exclude were untimely. The motion _in limine_ deadline was on June 12, 2026; the [_Daubert_](https://www.law.cornell.edu/wex/daubert_standard) motion deadline was on June 30, 2026. These motions were filed on June 30, 2026. Defendants argued that these motions are motions _in limine_, not _Daubert_ motions, and thus were filed after the applicable deadline. The Court is not persuaded by Defendants' arguments. As shown by the Court's analysis below, the parties primarily dispute whether the experts' opinions are admissible under the standards set forth in [Rule 702](https://www.law.cornell.edu/rules/fre/rule_702#:~:text=Rule%20702%20sets%20forth%20the,is%20a%20relatively%20narrow%20inquiry.) and _Daubert_. Accordingly, the Court finds that the motions were properly filed as _Daubert_ motions, and thus were timely filed.

The Court next addresses the substance of Plaintiff's motions to exclude

### **A. Motion to Exclude the Opinions of Jeffrey Martin**

Martin defines "human factors" as "the application of the widely accepted science of human capabilities and limitation in interaction with the environment."

Plaintiff sought to exclude two out of four of Martin's opinions. The first opinion which Plaintiff sought to exclude is as follows:

**"Henson's continued forward movement toward Deputy Derderian, combined with the reported proximity, i.e., eight feet, combined with the movement of Henson's right arm, would increase the likelihood that a similarly situated deputy would perceive those as an imminent threat of death or serious bodily injury due to how people—including peace officers—use 'affordance perception' and 'movement perception.'"**

The second opinion Plaintiff seeks to exclude is as follows:

**"Deputy Derderian's stated reasons for firing the second two shots were typical of how peace officers apply the cognitive and perceptual strategies in responding to time-pressured situations, including "situation awareness" and affordance perception."**

Plaintiff contended that these two opinions are not "the result of reliable scientific principles reliably applied." The Court agreed. In arriving at each of these opinions, Martin largely recites Derderian's account of what he observed and felt; Martin fails to explain how his expertise allows him to draw conclusions about how typical peace officers would act or perceive threats. For example, in reaching the first opinion, Martin recounts in detail how "Deputy Derderian reported he perceived the situation." Although Martin then goes on to cite to "video evidence [depicting] Henson stepping forward with his right forearm held across the front of his torso with his right hand concealed inside his jacket," Martin does not use any identifiable methodology to connect this observation to the ultimate conclusion that "a similarly situated deputy would perceive those as an imminent threat of death or serious bodily injury."

Similarly, in reaching the second opinion, Martin lists "Deputy Derderian's stated reasons for firing the last two rounds." He recounts that Derderian stated that he "noticed that Henson retained the perceived weapon, was running toward the Shell station where he believed other people to be, and that Henson would be able to harm others in that immediate area." Finally, Martin asserted that Derderian stated "that when Henson began his 'full sprint' toward the Shell station, he had the physical ability to reach the others and harm them." Martin's opinion thus consists almost entirely of repeating Derderian's testimony; Martin did not explain how he applied any expertise in evaluating this testimony and reaching a conclusion. Thus, Martin's ultimate opinion that Derderian's "stated reasons for firing the last two shots were typical of how peace officers apply the cognitive and perceptual strategies in responding to time-pressured situations" is no more than _ipse dixit._

In sum, because Martin has failed to "explain the methodology he followed to reach his conclusions," the Court concluded "that there is simply too great an analytical gap between the data and the opinion proffered."

### **B. Motion to Exclude the Opinions of Kris Mohandie**

Defendants' expert Kris Mohandie is a licensed psychologist. Mohandie reviewed the documents filed in this action, police reports, various interviews and depositions of witnesses and Derderian, video footage, and other materials to form his opinions in this case. Mohandie formed three opinions, all of which Plaintiff sought to exclude.

#### **1. Mohandie's First and Second Opinions**

Plaintiff sought to exclude Mohandie's first opinion, which is as follows:

**"The decedent, Henson, committed suicide by cop during the incident. Suicide by cop is a method of suicide that occurs when an individual engages in threatening (actual, apparent, and/or feigned) behavior to cause law enforcement to use deadly force against them as part of their intent to commit suicide. Henson purposefully and deliberately provoked his death at the hands of law enforcement. His death is subject precipitated by definition and fact pattern."**

Plaintiff also sought to exclude Mohandie's second opinion, which is as follows:

**"He was under the influence of and/or coming down from methamphetamine. Noted behavior is consistent with his methamphetamine use disorder and methamphetamine intoxication. He was violent, threatening, impulsive, suicidal, and aggressive. Methamphetamine use issues are associated with poor judgment, impulsive, and dangerous, high-risk and violent behavior. Use of methamphetamine- whether suicidal or not- can lead a person to behave very impulsively, unpredictably, and aggressively as Henson did in this case. . . . He was a danger to others as well as himself, and presented a risk of violence and harm to anyone in his immediate surroundings, including first responding deputies, as well as any people who might be in the vicinity-such as the gas station/convenience store."**

Plaintiff sought to exclude both of these opinions on similar grounds: Plaintiff contended that evidence going to whether Decedent died via "suicide by cop," and whether Decedent was under the influence, is irrelevant and prejudicial. According to Plaintiff, Decedent's state of mind, as well as whether Decedent was under the influence, are both irrelevant because "evidence of facts and circumstances not known to Deputy Derderian during his encounter with Henson are categorically irrelevant."

However, the Court found that evidence of Decedent's state of mind and state of intoxication is relevant to show how Decedent was acting at the time of the incident, which is in turn relevant to the issue of whether Derderian acted reasonably.

Plaintiff appeared to concede that such evidence can be relevant, but only when the parties dispute the events surrounding the incident. Plaintiff distinguishes this case by leaning heavily on the fact that video evidence of the incident exists. Plaintiff contended that the existence of a video means that Decedent's actions "cannot be plausibly disputed," rendering evidence going to Decedent's mindset or intoxication irrelevant.

The Court did not agree that a video is sufficient to place the events leading up to the shooting beyond dispute. Even with a video, the parties may still disagree on a number of different relevant aspects of the incident, like Decedent's demeanor or facial expressions which may not be adequately captured by video, or any of Decedent's actions which may not have been in frame of the video. Evidence that can show how Decedent was acting at the time of the incident, including evidence going to Decedent's state of mind and state of intoxication, is thus still relevant.

Plaintiff additionally sought to exclude Mohandie's first opinion—his suicide by cop theory—on the grounds that it is unreliable. Plaintiff characterizes Mohandie's opinion that Decedent intended to commit suicide by cop as an attempt to exercise "supernatural mind-reading powers." However, Mohandie, in his report, outlines in detail the facts which have informed his conclusion, citing to video evidence of Decedent's actions, as well as the interviews of Derderian and other witnesses who recounted the statements attributed to Decedent and Decedent's purported actions. Accordingly, the Court found that Mohandie's opinion about Decedent's state of mind is grounded in sufficient facts and data about Decedent's behavior.

Finally, in his papers and at the hearing, Plaintiff contended that Mohandie's opinion that Decedent "was violent threatening, impulsive, suicidal, and aggressive," which "is consistent with his methamphetamine use disorder and methamphetamine intoxication," is inadmissible. Plaintiff argued that "any expert or non-expert testimony that purports to determine what any drug 'caused' Henson to do or not to do would be inadmissible speculation." But for the reasons stated above, Decedent's state of intoxication is relevant to show how he may have been acting, including that he was more likely to act violently or aggressively. To the extent Mohandie seeks to opine on causation rather than association, Plaintiff may raise objections at trial.

In sum, the Court concluded that Mohandie's first and second opinions are relevant, helpful to the jury, supported by sufficient facts and data, and not unduly prejudicial.

#### 2. Mohandie's Third Opinion

Finally, Plaintiff sought to exclude Mohandie's third opinion, which is as follows:

"**There were no verbal or other available interventions that would have been successful under the circumstances that Henson created in this situation. First responders attempted to de-escalate him in multiple ways. Time, distance, willingness to talk, and desire to live are essential variables to a peaceful resolution that are determined by the suspect's behavior and motivation. Henson did not indicate any peaceful method to resolve this incident and forced the confrontation through his actions. There were a number of high-risk indicators present in this case that indicated a low likelihood of a successful verbal outcome, the most significant being Henson's suicidal state of mind (death wish), his unwillingness to submit to arrest, fueled by his methamphetamine abuse issues, which rendered him unwilling and incapable of being reasoned with.**"

As support for his opinion that there "were no verbal or other available interventions that would have been successful, Mohandie cited to one 2010 study he conducted, where he concluded that "where crisis negotiation and verbal techniques were attempted with SBC [suicide by cop] subjects, they made no significant difference in outcome."

However, Plaintiff pointed out that the conclusion of Mohandie's 2010 study is unsupported by the underlying data. Mohandie's 2010 study examined a set of 707 officer-involved shootings, where lethal or less-lethal force was used. Mohandie testified that only 1% of the sample involved no use of force; indeed, they "were specifically targeting shootings as opposed to other types of events that would be broader." Mohandie identified a subset of the 707 shootings as involving suicide by cop. He then compared the suicide by cop shootings where verbal strategies were used, to those where they weren't used, and found that there was no meaningful difference in outcomes. But importantly, because the original dataset included only officer-involved shootings, Mohandie's comparative analysis cannot support any reliable conclusion about the success of verbal strategies in fully deescalating suicide by cop scenarios.

Still, Mohandie leveraged this comparative analysis in forming his opinion that "there were no verbal or other available interventions that would have been successful under the circumstances that Mr. Henson created in this situation." In other words, Mohandie unreliably applied his 2010 study, which involved only suicide by cop scenarios resulting in police shootings, to form an opinion about whether suicide by cop scenarios could end in deescalation.

Defendants wholly failed to address Plaintiff's critique that Mohandie's reasoning is "profoundly flawed" because "from a sample that generally excluded de-escalated incidents, Mohandie purports to conclude that de-escalation is ineffective."

## **Held**

- The Court granted Plaintiff's motion to exclude certain opinions by Jeffrey Martin.
- The Court granted in part and denied Plaintiff's motion to exclude opinions by Kris Mohandie.

## **Key Takeaway**

A court may conclude that there is simply too great an analytical gap between the data and the opinion proffered. To avoid such a lacuna, the proponent of expert testimony must explain the methodology the experts followed to reach their conclusions and point to any external source to validate that methodology. The reasoning between steps in a theory must be based on objective, verifiable evidence and scientific methodology of the kind traditionally used by experts in the field.

## **Case Details:**

| Case Caption: | Westley Henson V. County Of Los Angeles |
| --- | --- |
| Docket Number: | 2:24cv8883 |
| Court Name: | United States District Court for the Central District of California |
| Order Date: | August 07, 2026 |

---

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