ShotSpotter Audio Evidence Helps Secure Murder Conviction

In August 2023, an argument between Irv Duff and his girlfriend began in the stairwell of her Southwest Washington, D.C., apartment building. During the argument, Duff knocked over a neighbor’s grill. The neighbor, victim Darnell Gibson, confronted Duff and the two men continued the conflict outside on the street. Duff called his girlfriend to warn her that “there was about to be a shootout.”

Moments later, Duff fired 23 rounds of automatic gunfire in three rapid bursts toward Gibson, striking him three times in the upper torso, fatally wounding him. Duff fled the scene and called his girlfriend again, urging her not to talk to the police and instructing her to blame someone else for the shooting.

ShotSpotter detected the gunfire and generated a real-time alert documenting 23 shots fired in three distinct bursts. The alert was automatically tagged as both “high capacity” and “full auto,” providing responding officers and investigators with immediate, detailed information about the scale and nature of the shooting.

At trial, Duff claimed he acted in self-defense and denied discussing the shooting during phone calls with his girlfriend. Prosecutors from the United States Attorney’s Office for the District of Columbia submitted the ShotSpotter audio recording as evidence to challenge those claims.

The recording captured three distinct bursts of automatic gunfire, contradicting Duff’s testimony that he pulled the trigger only once. It also established the precise timing of the shooting, placing it squarely between two phone calls Duff made to his girlfriend, consistent with witness testimony. In addition, the recording documented no other gunfire during the incident, undermining the defense’s suggestion that the victim had fired a weapon.

Walter Collier of SoundThinking testified as a Custodian of Records, explaining the operation of ShotSpotter technology and authenticating the audio recording for the court. Prosecutors built their case through testimony from expert witnesses, the officers and detectives who investigated the homicide, Duff’s girlfriend, who corroborated the phone calls, and the victim’s girlfriend, who testified that Mr. Gibson was unarmed.

On June 23, 2026, the jury found Duff guilty of second-degree murder while armed and four related firearms offenses.