News - York Digital Forensics Laboratory

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The YDFL Assists in a Maryland Frye-Reed Hearing Challenging FBI-CAST Drive Testing.

Annapolis, MD

William E. Folson, Chief Forensic Examiner for the York Digital Forensics Laboratory, provided crucial testimony in a Frye-Reed hearing held in the Circuit Court for Anne Arundel County, Maryland.

The Maryland Office of the Public Defender is seeking to exclude the testimony from an agent with the Federal Bureau of Investigations – Cellular Analysis Survey Team (FBI-CAST). At issue, is the FBI’s use of JDSU drive testing as a means to narrow down the geographic location of a cell phone at the time an incident occurred.

JDSU drive testing is a method whereby a cell phone and specialized software is utilized to map the Radio Frequency (RF) footprint of a cell tower. The FBI contends that the RF footprint obtained from a drive test conducted ten months after an incident occurred, is a reliable predictor of what the RF footprint would have been at the time of the incident.

William Folson, testifying on behalf of the defense, disagreed with the FBI’s assertion that they can predict the historical RF footprint of any cell tower ten months after an incident. Folson pointed out in his testimony that RF signals are dynamic in nature, and therefore their coverage cannot be predicted; historically or in real-time, and that the FBI's methodology fails to take into account numerous factors that can interfere with RF signal coverage, such as the weather, equipment modifications to the cell tower, changes in power output, and man-made obstacles like tall buildings.

In addition to the FBI agent, the prosecution called upon an RF engineer from T-Mobile to help bolster the FBI’s claims; however, on cross-examination, the RF engineer could not provide any known margin of error rate for JDSU drive testing or point to any scientific peer-reviewed studies that support the reliability of JDSU drive testing, when used in a criminal investigation. The FBI agent, when cross-examined, also could not provide any scientific basis for using drive testing or identify any research to support drive testing being accepted as a reliable forensic methodology, within any scientific field.

The issue of drive testing is currently under review by the judge in the case and a final decision whether to allow drive-testing testimony at trial, is pending.