Opinion ID: 2809688
Heading Depth: 1
Heading Rank: 5

Heading: Expert Witness Slide Presentation on DNA

Text: Appellant contends that the government’s expert should not have been allowed to use a demonstrative aid (a slide show presentation) to help explain DNA testing to the jury. A demonstrative aid can be used “if it is sufficiently explanatory or illustrative of relevant testimony in the case to be of potential help to the trier of fact,” but “may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice.” Sheffield v. United States, 111 A.3d 611, 625 (D.C. 2015) (internal quotation marks omitted). “[W]e review a trial court’s decision to admit or exclude demonstrative evidence for abuse of discretion.” Lloyd v. United States, 64 A.3d 405, 409 (D.C. 2013). The slide show contained information about the characteristics of DNA, how it is collected and tested, and how test results are analyzed. Appellant contends that it was misleading because it did not discuss false positives, failed to explain that some people leave more DNA on objects than others, lacked sufficient 17 information regarding error rates of DNA testing, and did not address why appellant’s DNA was found on the handgun’s trigger but not the handgrip. The trial court, however, found that the slide show would be helpful to the jury and was not misleading. The court also noted that any issues with DNA testing that were not addressed in the slide show could be brought up in crossexamination, and appellant’s trial counsel focused on those topics when crossexamining the government’s expert. The court also gave an instruction before the slide show was displayed to the jury, as suggested by this court in Lloyd, see 64 A.3d at 410, explaining that the slide show was being used for demonstrative purposes and stating, “[I]f there’s any discrepancy between the evidence that was admitted and the demonstrative exhibits, . . . you should consider only the evidence that’s been admitted in your deliberations.” Under these circumstances, the trial court’s decision to allow the government to use the slide show was not an abuse of discretion.