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WO

IN THE UNITED STATES DISTRICT COURT

FOR THE DISTRICT OF ARIZONA

Leslie A. Merritt, Jr.,

Plaintiff,

v. 

State of Arizona, et al.,

Defendants.

No. CV-17-04540-PHX-DGC

ORDER 

Plaintiff moves the Court to reconsider its ruling that DPS criminalist Liza Peloza 

may testify about the ballistics test she performed as documented in her report. Doc. 390. 

The motion is fully briefed (Docs. 406, 408, 426), and oral argument has not been 

requested. For reasons stated below, the Court will grant the motion.

I. Background.

On September 18, 2015, DPS criminalist Christopher Kalkowski determined that 

the bullets from the I-10 freeway shootings were forensically linked to Plaintiff’s Hi-Point 

C9 9mm handgun. Doc. 265-1 at 72. Because the Hi-Point 9mm has a slightly oversized 

barrel, the gun is capable of firing both 9mm (.355) and .357 caliber bullets. Doc. 406 at 5. 

Peloza test fired .357 caliber bullets from Plaintiff’s gun for purposes of her ballistics 

comparison “in order to obtain a more complete representation of the individual 

characteristics left on bullets fired from [Plaintiff’s gun.]” Doc. 383-3 at 90. Peloza used

procedures from a recent study by one of Plaintiff’s experts, Lucian Haag. Id. (citing 

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“Hi-Point C9 9mmL Study 5 Consecutive Barrels,” Association of Firearm and Tool Mark 

Examiners (“AFTE”) Forum); see Doc. 426-1. According to Peloza, “[t]he study 

determined that firing a .357 caliber bullet . . . through the Hi-Point model C9 would result 

in the bullet making complete contact with each of the lands of the barrel; thus, providing 

a more complete ‘picture’ of the individual markings made by the firearm.” Doc. 383-3 

at 90.

In her report dated June 16, 2016, Peloza describes the results of her testing as 

follows:

Using laboratory ammunition components, a 357 caliber bullet was loaded 

into a 9mm Luger caliber cartridge case and test fired. Two test bullets were 

collected and labeled[.]

Comparison of [two 9mm caliber bullets identified as having been fired from 

Plaintiff’s gun] to the newly fired ‘357 bullets’ . . . revealed additional areas 

of agreement which further affirm the identifications made by [Christopher] 

Kalkowski[.]

Id.; see id. at 24 (Peloza’s June 13, 2016 report stating that “[t]he ‘357 bullets’ 

were . . . compared to the previously test fired ‘9mm bullets’ . . . strictly for the purpose of 

providing additional documentation of the identifications previously made by C. 

Kalkowski[.]”) (internal references omitted).

Defendant identified Peloza as a fact witness and disclosed the report of the test she 

performed using .357 caliber bullets. Docs. 383 at 3, 383-3 at 24. Plaintiff moved to 

exclude Peloza’s opinions because she was never disclosed as an expert witness. Doc. 290 

at 2. On September 4, 2020, the Court found that Peloza’s testimony about her report was 

in fact expert testimony under Federal Rule of Evidence 702, but that Defendant’s failure 

to disclose her as an expert witness was harmless and she therefore may testify at trial. 

Doc. 387 at 3 (citing Fed. R. Civ. P. 37(c)(1)). The Court did not address whether her 

proposed testimony satisfies the requirements of Rule 702. See Docs. 382 at 4-5, 387 at 3. 

Plaintiff now moves to preclude Peloza’s testimony under Rule 702, arguing that it

is not based on an accepted methodology for firearms identification. Doc. 390 at 2-5. The 

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Court directed Defendant to file a response, and Defendant did so on September 25, 2020. 

Doc. 406. Plaintiff replied one week later, and Defendant filed a sur-reply on October 14. 

Docs. 408, 426.

1

II. Relevant Legal Standards.

Under Rule 702, an expert may offer “scientific, technical, or other specialized 

knowledge” if it “will assist the trier of fact to understand the evidence,” provided the 

testimony rests on “sufficient facts or data” and “reliable principles and methods,” and 

“the witness has reliably applied the principles and methods to the facts of the case.” 

Fed. R. Evid. 702(a)-(d). The proponent of expert testimony has the ultimate burden of 

showing that the proposed testimony is admissible. See Cooper v. Brown, 510 F.3d 870, 

942 (9th Cir. 2007); Lust v. Merrell Dow Pharms., Inc., 89 F.3d 594, 598 (9th Cir. 1996).

The admissibility of expert testimony under Rule 702 is a preliminary question the 

Court must decide under Federal Rule of Evidence 104(a), and the Rule 104(a) decision 

must be made by a preponderance of the evidence. See Daubert v. Merrell Dow Pharms., 

Inc., 509 U.S. 579, 592 & n.10 (1993); Bourjaily v. United States, 483 U.S. 171, 175-76 

(1987). Some cases mistakenly suggest that some of the elements in Rule 702 are jury 

questions – that whether an expert’s opinion is based on reliable principles and methods, 

and whether those principles and methods have been applied to the facts of the case 

reliably, go to the weight of the evidence and should be decided by the jury after cross 

examination and argument at trial. But the requirements of Rule 702 are conditions for 

admissibility, and the Supreme Court has made clear that “the trial judge must determine 

at the outset, pursuant to Rule 104(a),” whether the expert’s testimony is admissible under 

Rule 702. Daubert, 509 U.S. at 592; see id. at 597 (the trial court acts as a gatekeeper to 

1 Plaintiff further argues that Peloza impermissibly seeks to testify about an 

examination of the evidence bullets using an Evofinder. Doc. 390 at 5-6. Ballistics 

evidence generally is analyzed manually using an optical microscope. See United States 

v. Johnson, No. (S5) 16 CR. 281 (PGG), 2019 WL 1130258, at *8 (S.D.N.Y. Mar. 11, 

2019). An Evofinder is an automated ballistic identification system that assertedly allows 

an examiner to make a more accurate identification than a traditional microscope. 

See Docs. 390-5 at 4-5, 406 at 3 n.1; Evofinder, Automated Ballistic Identification, 

http://evofinder.com/technology/ (last visited Oct. 21, 2020). Defendant makes clear in its 

response that Peloza will not testify about use of an Evofinder. Doc. 406 at 2-3. 

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ensure that “an expert’s testimony both rests on a reliable foundation and is relevant to the 

task at hand”). Thus, the Court’s task in this order is to determine whether Defendant has

shown by a preponderance of the evidence that the requirements of Rule 702 have been 

satisfied with respect to Peloza’s testimony. See id. at 592 n.10; Bourjaily, 483 U.S. 

at 175-76; Davis v. McKesson Corp., No. CV-18-1157-PHX-DGC, 2019 WL 3532179, 

at *3-4 (D. Ariz. Aug. 2, 2019).

III. Discussion.

Plaintiff contends that Peloza’s comparison of evidence bullets with test-fired 

bullets of a different caliber is an experimental methodology that is not generally accepted 

in the forensic science community. Doc. 390 at 2-3. Plaintiff claims that Haag’s study 

involving the use of a different caliber bullet, which Peloza cited in her report, was an 

academic endeavor designed to find out, theoretically, whether a larger diameter bullet 

would engage more snugly against the barrel of the gun when fired. Id. at 4 (citing 

Doc. 390-5 at 11-12). Plaintiff notes that Haag merely shared the study “anecdotally with 

colleagues in a chat room for members of [the AFTE,]” and that the study has not been 

published and peer-reviewed. Id.

Defendant counters that Peloza’s report is based on a pattern-matching firearm 

examination, which the AFTE has recognized as an approved forensic method. Doc. 406 

at 5; see Peloza Decl., Doc. 426-7 at 7. Under the pattern-matching method, examiners use 

a high-powered microscope to determine whether there is “sufficient agreement” between 

the unique surface contours of two firearm toolmarks. Id. Defendant asserts that patternmatching is an accepted and reliable ballistics methodology, noting that federal courts have 

found expert testimony based on the pattern-matching methodology admissible under 

Rule 702 and Daubert. Docs. 406 at 6-7, 426 at 3-6.

But Peloza, by her own admission, used a different method – comparing evidence 

bullets with test-fired bullets of a different caliber. Peloza states in her June 9, 2016 

worksheet that, “[b]ased on a method used and results obtained in a recent study [by Lucien 

Haag,] it was decided to use that same method in order to obtain more complete markings 

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on test fired bullets.” Doc. 408-7 at 2. Defendant has not shown that this new method is 

generally accepted by the community of firearms and toolmark examiners, that Haag’s 

study has been published and peer-reviewed, or that there is a known or potential error rate 

when comparing bullets with different calibers. See Daubert, 509 U.S. at 593-94.

Defendant notes that Plaintiff fails to identify a single case in which forensic 

ballistics testimony was excluded under Daubert, and that the pattern-matching method 

has been tested and has a very low error rate. Doc. 406 at 6 & n.2. But Plaintiff is not 

challenging testimony based on the well-established pattern-matching method; he 

challenges Peloza’s use of the new method purportedly proposed by Haag. Doc. 408 at 4. 

Defendant further asserts that the AFTE Journal meets the Daubert peer review element

(Doc. 426 at 6), but Haag shared his study “informally with colleagues in an online forum”

(Doc. 408-2 at 3). Haag has made clear that his study “has not been peer-reviewed,” that 

its purpose “was informational only[,]” and that the “technique of the study was not 

intended or validated for any forensic use in actual criminal case work.” Doc. 408-2 at 3.

What is more, Haag’s study was a barrel-to-barrel comparison, not a bullet-to-bullet 

comparison in which different size bullets were used. The study is titled “Hi‐Point C9 

9mmL Study 5 Consecutive Barrels.” Doc. 426-1 at 8 (emphasis added). The purpose was 

“[t]o investigate the possibility of carry-over (sub-class characteristics) between 

consecutively manufactured 3-Left C9 High-Point barrels.” Id. at 10; see Doc. 408-2 at 2 

(“In April 2016, I conducted an informal study to determine if bullets fired from 

consecutively manufactured Hi-Point 9mm barrels would contain reproducible 

markings.”). Peloza relies on a supplement to Haag’s study in which he used .357 caliber 

bullets “as a means of obtaining the maximum amount of striated markings for the purpose 

of evaluating sub-class or ‘carry-over’ from the rifling tool.” Doc. 426-1 at 275. The .357 

bullets were not used to make a bullet-to-bullet comparison of different caliber bullets to 

determine whether the same gun had fired the bullets.

Defendant relies on the AFTE’s “sufficient agreement” pattern-matching method. 

Doc. 426 at 4; see AFTE, Theory of Identification as it Relates to Toolmarks, 

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https://afte.org/about-us/what-is-afte/afte-theory-of-identification) (last visited Oct. 21, 

2020). “‘[S]ufficient agreement’ is related to the significant duplication of random 

toolmarks as evidence by the correspondence of a pattern or combination of patterns of 

surface contours. Significance is determined by the comparative examination of two or 

more sets of surface contour patterns comprised of individual peaks, ridges and furrows. 

Specifically, the relative height or depth, width, curvature and spatial relationship of the 

individual peaks, ridges and furrows within one set of surface contours are defined and 

compared to the corresponding features in the second set of surface contours.” Id.

Defendant has not shown that this comparison of surface contours is a reliable 

method of pattern-matching when different size bullets are compared. Nothing is offered 

to account for the likely larger peaks, ridges, and furrows within the larger caliber bullet, 

or to extrapolate from the smaller markings on the smaller caliber bullet. Defendant states 

that “[t]he reason that Haag and the other forensic scientists in this case were able to make 

an identification of the source gun is because the markings themselves are what matter for 

the science of forensic firearm examination.” Doc. 426 at 4. But again, the markings on 

different caliber bullets will have different sizes – this is the reason Peloza used larger .357 

caliber test-fired bullets – and Defendant has not shown that a comparison of the 

differently-sized markings is a reliable pattern-matching method to determine whether a 

particular gun fired certain bullets.

Peloza states that “it is not uncommon to do ten or more test firings until an examiner 

obtains a test fire that has good markings for comparison purposes.” Doc. 426-2 at 7-8. 

But she does not say that these test fires commonly use different caliber bullets. Peloza

provides no persuasive explanation for her statement that “[t]he analysis of the striation, 

markings, and patterns on the bullet are still done through the pattern-matching method 

and do not change simply because [a] .357 bullet was used to obtain the test markings.” 

Id. at 7.

Similarly, the Court finds the statement of DPS forensic scientist John Maciulla that 

“there is nothing about the increase in the .002 [caliber] that changes the science itself of 

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pattern matching and comparing the markings on the fired bullets” to be conclusory. 

Doc. 426-1 at 6. The statement purportedly is based Maciulla’s “training, knowledge, and 

experience of the pattern matching method[,]” but he identifies no specific training, 

knowledge, or experience using different caliber bullets to make a firearms toolmark

identification. Id.; see In re Bard IVC Filters Prods. Liab. Litig., No. MDL 15-02641-PHX 

DGC, 2018 WL 495189, at *3 (D. Ariz. Jan. 22, 2018) (rejecting expert testimony where 

the expert provided no information from which the court could conclude that his own 

experiences or training as a physician provided “sufficient facts and data” to support an 

opinion on complication rates) (quoting Fed. R. Evid. 702(b)). Maciulla further states in 

conclusory fashion that Haag’s study was “adequate to serve as a validation study for 

Peloza’s .357 analyses.” Doc. 426-1 at 6. The Court finds Haag’s statement to the contrary 

(Doc. 408-2 at 3) to be more persuasive because he performed the study and knows better 

than Maciulla the study’s scope and purpose.

DPS forensic scientist Aaron Brudenell has testified that Peloza’s analysis of the 

test-fired .357 bullets “is consistent and in compliance with [his] training, experience, and 

knowledge of the pattern matching method.” Doc. 426-2 at 3. But Brudenell also provides 

no specific training, knowledge, or experience with using different caliber bullets to make 

a firearms toolmark identification.

Defendants have failed to show, by a preponderance of evidence, that Peloza’s 

testimony about her .357 analysis rests on sufficient facts and data, reliable principles and 

methods, or reliable principles and methods applied reliably, as required by Rule 702(b)-

(d). The Court accordingly will grant Plaintiff’s motion and preclude Peloza’s testimony 

in this regard.

IT IS ORDERED that Plaintiff’s motion to preclude testimony of Lisa Peloza

(Doc. 390) is granted.

Dated this 22nd day of October, 2020.

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