Fraud Expert Witness Permitted to Interpret Slang Terminology Captured on Undercover Footage

    Fraud Expert Witness Permitted to Interpret Slang Terminology Captured on Undercover Footage

    Court: United States Court of Appeals for the Eleventh Circuit
    Jurisdiction: Federal
    Case Name: United States v. Delva
    Citation: 2019 U.S. App. LEXIS 12856


    Following an undercover federal investigation, the defendants were convicted of seven identity theft and tax fraud crimes. The government retained a fraud expert witness to substantiate its case. The defendants challenged the fraud expert’s testimony on appeal.

    The Fraud Expert Witness

    The government’s fraud expert was a police detective who had been assigned to the IRS Identity Theft Task Force for several years. The fraud expert received training on identity theft incidents from a number of different agencies. Over the course of his career, he conducted 75+ fraud investigations, including 50 tax fraud cases. The expert also listened to 30+ prison calls made by defendants charged with stolen identity refund fraud and debriefed 20+ cooperating defendants. The expert had experience teaching fraud courses to other police departments and universities as well as experience testifying in federal court.

    The Fraud Expert Witness’s Testimony

    The expert generally described how “stolen identity refund fraud” works and the general practices fraudsters employed in these cases. The expert testified that the perpetrators committing “stolen identity refund fraud” obtained PII (names, dates of birth, and Social Security numbers) from multiple sources. He also testified that the documents sealed in this case were consistent with the type of documentation he had seen in similar cases. The fraud expert also offered insight into common slang terminology used by identity fraudsters in South Florida. The government played portions of a video of the defendants that was taken by an undercover agent and asked the expert to interpret various slang terms.

    The defendants asserted that the district court abused its discretion in permitting the government’s fraud expert to testify regarding identity theft and tax fraud. Furthermore, the defendants claimed that the fraud expert’s interpretations of terminology and jargon on the undercover video held no merit.


    The court noted that it was well established that experienced and qualified law enforcement officers could testify as experts to the interpretation of criminal communications and activities that the jury might not otherwise understand. A host of cases were cited in which numerous courts had held that there was no error in admitting such testimony, including United States v. Holt. The court believed that the district court did not abuse its discretion by admitting the fraud expert’s testimony regarding jargon used in stolen identity refund fraud cases because of his expertise and experience in the field. His testimony was deemed applicable to both in general and as it pertained specifically to individuals captured on the undercover video.

    The court further noted that the fraud expert’s methodology was credible, as his findings were based on his experience working on stolen identity refund fraud cases. The court pointed to the fraud expert’s experience researching, working undercover, listening in on prison calls, and debriefing the defendants charged with the crime. Additionally, the court observed that the fraud expert witness’s testimony about the slang used by the defendants could assist the jury in understanding how they were related to the terminology used in such fraud cases, noting that “[though it is possible for lay people to guess the meanings of slang words, the expert] could—based on [his] training and experience—interpret the meaning of the words more accurately than a lay person or the prosecutor,” again citing United States v. Holt.


    The court held that the expert’s testimony about the nature and practice of stolen identity tax refund fraud and associated slang terminology was relevant to the issues at hand and could assist the finder of fact. Thus, there was no error on the part of the district court in allowing his testimony.