Beyond the Gunshot: ShotSpotter Forensics in High-Profile Investigations

A retired career prosecutor who specialized in homicide trials and officer-involved shooting investigations. A retired ATF Deputy Assistant Director who had oversight of ATF’s National Programs, including NIBIN. And a forensic lab director who built one of the most advanced crime gun intelligence programs in the country. That combined expertise came together on our recent webinar, Beyond the Gunshot: ShotSpotter Forensics in High-Profile Gun Investigations, to share firsthand experience using ShotSpotter forensics in high-profile shootings.

Melissa Dooher, Senior Director of Forensics and Litigation Support at SoundThinking, spent 25 years as a prosecutor in Oakland, California, including four years embedded inside the Oakland Police Department as the sole charging attorney for homicides. Carlos Canino, Director of Customer Success at SoundThinking, is a retired ATF Deputy Assistant Director. Stephanie Stoiloff is Director of the Forensic Services Division at the Miami-Dade Sheriff’s Office, where she has built one of the country’s top crime gun intelligence programs.

The conversation delved deeper than just the fundamentals of the  Investigative Lead Summary (ILS) and Detailed Forensic Report (DFR). It looked into firsthand accounts of how a forensic lab structures a program around ShotSpotter® data, the impactful roles played by gunfire audio files and expert witness testimony, and the potential areas investigators could further leverage for a more exhaustive evidence collection.

Stoiloff’s team did not wait for a case to reach the courtroom to put ShotSpotter data to work. When Miami-Dade first incorporated ShotSpotter in 2017, there was insufficient consultation with the crime lab regarding technology support requirements. Stoiloff persisted, constructing an efficient program. She began with a pilot, subsequently convincing her agency to assign two NIBIN technicians and an intelligence analyst to effectively manage and optimize the wealth of data the system was producing.

That analyst function grew into a full Forensic Intelligence Unit embedded inside the Miami-Dade crime lab. The unit takes ShotSpotter data, NIBIN hits, crime scene evidence, video, and fingerprints from related incidents and builds what Stoiloff calls a crime gun event chart. Additionally, the unit runs daily intelligence calls with federal, state, and local partners.

Stoiloff calls this approach forensic-led policing. Instead of treating forensic evidence as something that only matters once a case is charged, her team uses it at the front end of an investigation to help direct resources. She noted that investigators now regularly ask how quickly evidence can reach the lab so they can find out whether it produced a NIBIN hit — a question she said she never expected to hear in more than 30 years in forensics.

Citing a Brookings Institution study, Canino noted that roughly 80% of gunfire incidents are never called in to 911, with rates reaching well into the 90% range in some communities characterized by a pervasive culture of under-reporting or that face issues due to limitations in their dispatching services capacity. Building a gun violence strategy without accessing complete data creates an inherently weakened foundation. Bridging the data gap with ShotSpotter helps build a successful strategy.

Canino framed the idea for building a strong strategy around the principle of people, process, and technology. Technology like ShotSpotter closes part of that gap, but only if the people and process around it are built to use it. Canino described this as building a continuous crime gun intelligence framework, one that looks different in every jurisdiction because each jurisdiction’s gun violence problem is different.

Dooher walked through the kinds of questions a Detailed Forensic Report (DFR) is built to help answer once a case moves toward trial, several with real-world texture:

·         Who fired first: In multiple-shooter incidents, the DFR can assist in determining the sequence of shots fired from various locations — crucial evidence for self-defense claims. Dooher pointed out that this type of analysis is most effective when the shooters are significantly distanced from one another, rather than trying to differentiate shooters positioned at an arm’s length apart.

·         Multiple firearms: Overlapping audio, where shots register faster than a single firearm could be fired twice, can support expert testimony that more than one weapon was involved.

·         Speed and direction of travel: In true drive-by shootings, where a vehicle is moving while shots are fired, the acoustic data can help establish direction and speed of travel. A scenario where the vehicle stops before the shooter fires would not generate this kind of moving data.

·         Cadence and pauses: Often the sheer number of shots fired or the intervals between them powerfully demonstrate the shooter’s premeditation and deliberation. Pauses between successive bursts of gunfire can provide supporting evidence that the shooter either reloaded the weapon or encountered a firearm malfunction.  

·         Sensor participation: Dooher described an intriguing case in which the final shot, amidst a series of many, was detected by only a few sensors in contrast to more than a dozen sensors that registered the previous shots. That distinction supported the prosecutor’s theory of an execution-style ending. A gunshot fired into the ground results in a significant portion of the sound waves being absorbed by the earth and the victim, resulting in a diminished detection range.

·         Firing position and movement: In one case Dooher prosecuted in Oakland, ShotSpotter data mapped a shooting that moved across roughly five to six city blocks as the defendant chased his victim on foot. The location analysis supported a premeditation and deliberation argument and corroborated the physical evidence.

Dooher shared two other cases that illustrate how compelling ShotSpotter evidence can be at trial.

In one case, two men parked driver’s side to driver’s side exchanged gunfire after an argument. Neither man was hit, but a passenger in one of the cars was killed. Both men claimed self-defense. The forensic analysis in the DFR showed both firearms discharging within milliseconds of each other. The timing undermined a claim of self-defense for either shooter, instead demonstrating mutual combat. Both defendants were convicted of homicide and sentenced to more than 25 years to life.

In a case previously referenced in SoundThinking’s St. Louis County resource, a domestic violence homicide involved 16 shots fired in three distinct volleys, with pauses of up to two seconds between them. The victim’s mother testified at trial to witnessing the shooting and suffering gunshot wounds herself. It would be unrealistic to expect her to recount the exact sequence of the gunfire during such a traumatic event. The audio recording did that work instead, supporting a first degree murder premeditation theory over the defense’s argument for heat-of-passion.

In closing the webinar, Dooher reiterated a few best practices for not only securing any transient evidence, but also in effectively utilizing the ShotSpotter evidence in light of the facts and legal issues:

·         Notify SoundThinking early, and always within 24 hours if an incident did not generate an alert

·         Flag high-profile cases and officer-involved shootings explicitly so they are prioritized correctly

·         Include full contact information with every request

·         Note relevant scene context: indoor or partially indoor shootings, shootings from or into a vehicle, suppressed or small-caliber firearms, and physical obstacles nearby

·         Include the ILS in every charging packet to ensure proper discovery practices

·         Preserve other timing evidence, including cell phone records, before retention windows close

·         If investigators or attorneys determine a DFR is necessary, plan ahead – forensic analysis and report production can take a few weeks

The panel’s core message extended beyond any single report or feature. Acoustic gunshot evidence is most powerful when it is built into a jurisdiction’s process from the start, rather than a late addition as a case is headed to trial. Whether that means a formal Forensic Intelligence Unit modeled on Miami-Dade’s or simply a habit of including the ILS in every charging packet, the agencies getting the most from ShotSpotter forensic data are the ones treating it as a standing part of the investigative workflow.