Monthly Archives: January 2012

Improving Arson Investigations

Discover Magazine recently published two articles about how recent scientific investigation has challenged the traditional principles and methodology of fire investigation. Spark of Truth: Can Science Bring Justice to Arson Trials? explains how these developments have occurred and Seven Myths About Arson debunks seven fire scene findings that have been used in numerous cases as evidence of arson.

In light of these articles being published and the recommendations of the Texas Forensic Science Commission discussed below, I have updated the Arson Resources page of the IDS forensics website with several new articles and resources. Take a look at the changes I have made!

On October 28, 2011, the Texas Forensic Science Commission recommended a review of arson convictions in the state to determine whether faulty science could have led to wrongful convictions. The State Fire Marshal’s Office and the Innocence Project of Texas will assist in the review.

Click here to read the Commission’s recommendations or visit the Innocence Project’s website for more information on the recommendations and the Cameron Todd Willingham case.

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Two Bullets, One Gun?

By Alyson Grine, Defender Educator, UNC School of Government

In State v. Britt, __ N.C. App. __, __ S.E.2d __ (Dec. 6, 2011) the North Carolina Court of Appeals addressed the admissibility of expert testimony regarding firearms and toolmark identification. The facts, in brief: Nancy Britt, a Wake County school teacher, was shot and killed while visiting her disabled sister in Lumberton. At the autopsy, a .25 caliber Winchester bullet was recovered from her body. The defendant, Myron Britt, was Nancy’s husband. Myron became a suspect when his brother, Dickie, told law enforcement that Myron had borrowed a .25 caliber pistol from him about five weeks before Nancy was killed. Dickie also told officers that two years previously, the same gun had accidentally discharged into a baseboard at their mother’s home. Officers recovered a .25 caliber Hornady bullet from the baseboard. SBI agents Theresa Tanner and Peter Ware compared the bullet from the decedent’s body and the bullet from the baseboard and concluded that they had been fired by the same gun.

The defendant made a pretrial motion in limine to exclude Agents Tanner and Ware’s firearm identification testimony. The trial judge decided to limit the State’s experts’ testimony to statements that the bullets were “consistent” and not allow them to testify that they had been fired from the same gun. However, after defense counsel said in opening statements that defense experts would testify as to their “opinion that you cannot make a match, that there [are] simply not enough points of comparison on the two bullets,” the trial judge reversed his ruling and allowed the State’s experts to testify to their opinions that the bullets were fired from the same gun. Their opinions were based upon the lands and grooves as well as microscopic striations and marks on each of the bullets—that is, the “toolmarks” left on the bullets from the firing of the gun. The defendant, in turn, offered the expert testimony of John Dillon, a former chief of the FBI’s firearms and toolmark unit, and William Conrad, a private consultant on firearms identification, that there were insufficient microscopic points of comparison between the two bullets to conclude that they had been fired from the same gun.

The defendant was found guilty of first-degree murder and sentenced to life imprisonment without parole. According to appellate counsel, the verdict hinged on the firearm identification testimony. “The State’s case was built on the SBI’s bullet comparison. Without the expert testimony of SBI Agents Tanner and Ware that the bullets matched, the State would have had no evidence connecting the murder with the only gun known to have been in Myron Britt’s possession.” (Appellant’s Brief, p. 13)

On appeal, the defendant argued that the trial judge erred in reversing his ruling on the motion in limine and attacked the reliability of the methodology as well as the agents’ qualifications to testify as expert witnesses. The Court of Appeals dismissed the reliability argument, stating that precedent supported the admission of expert testimony on firearms ID, and the defendant had not produced new evidence to challenge the reliability. The Court also rejected the defendant’s argument that the State’s experts were not qualified to testify. While the State did not present verification of one of the expert’s training and neither expert was a member of a professional organization, both experts explained how firearms and toolmark identification works and how they conducted their investigations. Thus, the Court found that they were better qualified than the jury to form an opinion and the trial court did not abuse its discretion in allowing them to testify.

What lessons might defenders take away from Britt? First, a trial judge may be willing to limit expert testimony about this methodology. (Sarah has posted trial counsel’s Motion to Exclude State’s Firearm Testimony in her Motions Bank as an aid.) The trial judge had misgivings about allowing the SBI firearms and toolmark identification testimony, and although he believed he was bound to admit it, he initially limited the testimony. “We should require more. But given [North Carolina] precedent…” (Tp. 4380) “[I]t’s a frightening prospect when you can’t testify to a statistical certainty under DNA analysis that a match is a certain match and you can do the exact same thing under ballistics testimony as subjective as that testimony might be. That’s concerning.” (Tp. 4381) (Appellant’s Brief, p. 14)

A defendant benefits significantly where testimony is limited to “these toolmarks are consistent with each other,” rather than “these toolmarks were made by the same gun.” Bullets or cartridge cases have consistent toolmarks, even if fired by different guns, if the guns have the same class characteristics (e.g., barrels of a particular caliber with a particular number of lands and grooves of a particular width and direction of twist), according to Professor Adina Schwartz of John Jay College of Criminal Justice, CUNY. (Schwartz has written widely on the unreliability of this forensic discipline, and Sarah Rackley has posted links to some of her articles  here.) Counsel might offer evidence of the hundreds of other firearms, with the same class characteristics as the gun in question, that were sold at the local Walmart in recent years, rendering the expert testimony merely speculative as to which gun or guns fired the bullets.

Second, if the defense succeeds in getting a ruling that limits the State’s experts to “consistency,” defense attorneys should refrain from forecasting or introducing defense expert testimony that the resemblances between the individual characteristics of toolmarks were not sufficient to justify an identification. Such testimony may open the door for the court to retreat from its consistency ruling and allow prosecution experts to testify to an identification. Meanwhile, according to Professor Schwartz, defense expert testimony is not likely to offer any advantage: “In most cases, defense experts will only be willing to testify to an ‘inconclusive’; such testimony adds nothing where a pre-trial ruling limits prosecution experts to testifying that marks on ammunition components are ‘consistent with’ each other because firearms and toolmark examiners use both terms  ‘consistent with’ and ‘inconclusive’ to mean that it is not possible to conclude that marks were made by the same gun, but only that the marks were made by a gun(s) with the same class characteristics.”

In rare cases, defense experts may be willing to go beyond an “inconclusive” and testify that the lack of resemblance between individual characteristics of the toolmarks is so great that ammunition components can be excluded from having been fired from the same gun. Even in this instance, however, it is generally inadvisable for the defense to put on its own testimony about individual characteristics. Professor Schwartz cautions that on cross, the prosecution will be able to bring out the fact that most firearms and toolmark examiners (including FBI examiners) do not exclude on the basis of individual characteristics. Additionally, the prosecution may point out the absence of any objective criteria for how much difference between individual characteristics is needed for an exclusion. Opening the door remains a concern as well; a trial judge is not likely to allow defense experts to testify that individual characteristics are so different as to justify an exclusion without allowing prosecution experts to testify that the individual characteristics are so similar as to justify an identification.

By contrast, Professor Schwartz advises that the defense should put on expert testimony, even if there is a pretrial consistency ruling, if the disagreement between defense and prosecution experts extends to whether toolmarks on ammunition components have the same class characteristics (in other words, whether the ammunition components could have been fired from the same type of gun): “Defense expert testimony about class characteristics will not open the door for prosecution experts to testify that individual characteristics justify an identification.”

A third important takeaway from Britt is that defenders should not give up on the reliability argument. Under Howerton v. Arai Helmet, Ltd., when presented with “compelling new perspectives on otherwise settled theories or techniques,” a trial court can look beyond precedent to determine whether an expert’s area of testimony is sufficiently reliable. 358 N.C. 440, 597 S.E.2d 674 (2004)(Appellant’s Brief, p. 25) In Britt, the defense introduced case law and law review articles discussing the unreliability of firearm and toolmark evidence. (Appellant’s Brief, p. 21) However, the Court of Appeals appeared to require a greater showing of the defendant, holding that “[i]n the instant case, however, defendant did not introduce any ‘new’ or ‘compelling’ evidence to the trial court.” Slip op p. 10. Defenders who wish to challenge the reliability of firearms toolmark identification may therefore need to introduce evidence of unreliability beyond written materials such as case law and law review articles. However, the reliability argument was undermined in Britt by the fact that the defense put on experts who had relied on the same or similar methodology as the State’s examiners.

Furthermore, in a previous post on expert testimony, I commented that following legislative changes to N.C. Evidence Rule 702(a), “Court actors should not presume that a method of proof that was deemed sufficiently reliable under the former North Carolina rule and Howerton will be admissible under the amended rule.” S.L. 2011-283 (H 542), as amended by S.L. 2011-317 (S 586), effective for actions arising (that is, offenses occurring) on or after October 1, 2011. The Britt case illustrates that it is not unusual for firearms and toolmark examiners to disagree about whether resemblances between individual characteristics are sufficient to show that ammunition components were fired from the same gun, giving rise to an argument that opinion testimony about whether toolmarks match does not meet the requirements of revised Rule 702(a): “The absence of an objective criterion for when the resemblances between toolmarks are sufficient for a match means that when examiners disagree, the discipline of firearms and toolmark identification has no resources for determining who is right,” according to Professor Schwartz.

Finally, while a consistency ruling is a victory for the defense, defenders should not give up on arguing for total exclusion of firearms and toolmark identification testimony because of the risk of unfair prejudice and confusion. Professor Schwartz advises: “The problems with allowing prosecution experts to testify that ammunition components were fired from a gun or guns with the same class characteristics are, first, there is no data on how many guns share the same class characteristics; second, jurors are likely to confuse testimony that the marks on ammunition components are consistent with testimony identifying ammunition components as having been fired from the same gun.” This gives rise to an argument under N.C. Evidence Rule 403 that the probative value of testimony about toolmarks is outweighed by the dangers of unfair prejudice and confusion of the jury and must, therefore, be excluded.

In writing this post, I drew on the brief by David Neal, counsel for the defendant-appellant, and notes by Professor Adina Schwartz of John Jay College of Criminal Justice, CUNY. I thank them for their insights.

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Crime Scene Investigation – New Website

As a follow-up to my post from earlier this week on crime scene investigation, I have created a website with articles and publications that describe best practices for physical evidence recognition, evidence preservation and collection, and crime scene documentation. I have posted standards and guidelines for crime scene investigation and other crime scene resources on this new page in the Indigent Defense Services forensics website, available here.

If you have feedback on the website or additional materials you’d like to see included, please send me an email or post a comment on the blog.

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Crime scene forensics: How does it work?

BBC News has posted a series of videos explaining how forensic tests are performed in crime labs on their Crime scene forensics: How does it work website. These short videos demonstrate various techniques including fingerprint comparisons, use of ninhydrin and superglue fuming (cyanoacrylate) to locate latent print evidence, firearm and projectile comparisons, and examination of pieces of evidence using specialized light sources. The website also contains a limited description of forensic DNA analysis.

The demonstration of these lab techniques should help attorneys understand the function and the limitations of such tests. Viewing the video demonstrations while reading the State Crime Lab technical procedures for latent evidence examination may help attorneys visualize the tests that the technical procedures describe.

Another section of the website provides a 360° crime scene demonstration, which gives a basic description of the phases of evidence collection, the techniques used to preserve evidence, and the roles of crime scene technicians.

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