Skip to content

Sexton v. State, 93 S.W.3d 96 (Tex. Crim. App. 2002)

Case (cite)
Sexton v. State, 93 S.W.3d 96 (Tex. Crim. App. 2002)
Type of proceeding
Type of claim
Type of claim (second claim)
Expert evidence ruling reversing or affirming on appeal:
What was the ruling?
Error to Admit
Type of evidence at issue:
Firearms identification
Defense or Prosecution Expert
Name of expert(s) who were the subject of the ruling
Ronald Crumley
Summary of reasons for ruling
The court held that the expert was qualified, but that his techniques were not reliable in this case because he did not have knowledge of the manufacturing process of the magazines and did not have the firearm to create test toolmarks. Further, the court disagreed with the expert's statement that his methods were 100% accurate because he did not have the firearm available for test marks.
The jurisdiction’s standard for expert admissibility at the time – list all that apply: (Frye), (Daubert), (Post-2000 Rule 702), (Other)
Second standard
Rule 702
Did lower court hold a hearing
Names of prosecution expert(s) two testified at hearing
Names of defense expert(s) who testified at hearing (or None).
Discussion of 2009 NAS Report (NAS2009)
Discussion of 2016 PCAST report (PCAST)
Discussion of error rates / reliability
Frye Ruling
Limiting testimony ruling
Language imposed by court to limit testimony
Ruling based in prior precedent / judicial notice
Daubert ruling emphasizing – which factors – (list 1-5)
(1); (2); (3)
Ruling on qualifications of expert
Ruling on 702(a) – the expert will help / assist the jury
Ruling on 702(b) – the testimony is based on sufficient facts or data
Ruling on 702(c) – the testimony is the product of reliable principles and methods
Ruling on 702(d) – reliable application of principles and methods to the facts of the case


“The potential rate of error factor weighs in favor of exclusion. Crumley testified that this technique is one hundred percent accurate. Vincent DiMaio, author of one of the treatises on which Crumley relied, testified that he could not be one hundred percent accurate in matching two cartridge cases based on their magazine markings unless he had the actual magazine. The Court of Appeals found it significant that DiMaio’s interest in firearms identification was only a hobby. DiMaio, the Court of Appeals noted, did not qualify as a firearm and toolmark expert,5 therefore his opinion should not discount the reliability of Crumley’s assertion that the technique employed was one hundred percent accurate.
Crumley’s bare assertion is one that the available literature contradicts, however. The literature says that these marks may enable an examiner to connect cartridge cases with the same weapon. The only literature that explains what circumstances make it possible for an examiner to do so requires that the examiner possess knowledge of the manufacturing process of the tool surface and have the tool available for creating test toolmarks. In this case, the magazine or magazines that made the marks upon which Crumley based his identification were not found by the police. Therefore Crumley was not able to make test marks for comparison. Also, Crumley did not say whether he was familiar with the manufacturing process of the magazine or magazines that he said left identifiable marks on the live rounds and cartridge cases.”