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Foundations of Firearms Audio Forensics Built by Dr. Robert Maher Will Continue to Be Important Forensic Tool as More Recording Devices Are Present at Crime Scenes

by Jo Ellen Nott

Dr. Robert Maher, electric and computer engineer who has researched and studied gunshot acoustics at the University of Montana, published the results of a two-year study on synchronizing and processing audio recordings of gunshots in 2018. His research was sponsored by a National Institute of Justice award.

For his paper “Advancing Audio Forensics of Gunshot Acoustics,” Maher and his assistants collected high-quality, repeated recordings of gunshots under controlled conditions and found that there are both similarities and differences between shots fired from the same gun. These data are important because they can help to identify the source of a gunshot and determine whether multiple shots were fired.

Maher also studied the limitations of forensic interpretation from common recording devices such as cellphones, land-mobile radios, and personal audio recorders. The engineer found that these devices can introduce distortions and other traces into audio recordings making it challenging to analyze them accurately. In an important step of his research, Maher also developed new ways to synchronize and process audio recordings from multiple devices.

Maher’s research has been used in several high-profile criminal cases, including the trial of Cleveland police officer Michael Brelo who fired his Glock 17 pistol 49 times, including at least 15 shots after he reloaded and climbed onto the hood of the suspect’s car, to shoot into the front seat and kill the unarmed driver and his passenger. By this time, the 12 other responding officers had stopped firing.

During the 2015 trial, Maher was called as an expert audio witness by the prosecution. Attorney Collin Holloway, writing about the trial on the ExpertPages Blog, related that Maher was asked to listen to a recording of the incident taken by the Bratenahl Police Department radio pulled from the dashboard camera of one of the squad cars. Maher had previously analyzed the audio in his lab and testified on the stand that 15 of the 18 shots were fired from the same gun. The interval and sound of the shots backed his finding.

Brelo’s defense challenged Maher about the ambient noise that could impact a sound analysis—such as police sirens, distance, and other gun shots—but Maher maintained that the shots had come from the same gun despite those factors, according to Holloway. His findings were corroborated by independent FBI investigations that came to the same conclusion.

Despite the expert testimony, The New York Times reported that Brelo was acquitted of manslaughter by an Ohio judge.   


Sources: ExpertPages Blog, Forensic Magazine, Montana State University, The New York Times, Office of Justice Programs

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