Traffic detective: airbag control module shows Mazda near 60 mph before crash, 42 mph at impact
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Summary
Detective Brad Armstrong testified ACM data from the Mazda (Unit 1) recorded about 60 mph five seconds before deployment and roughly 42 mph at the moment the module recorded impact; he said brakes were applied and that the defense could not obtain ACM data from Unit 2.
Detective Brad Armstrong of the San Antonio Police Department's Traffic Investigation Detail testified that vehicle data downloaded from the Mazda involved in the Oct. 13, 2023 collision showed speeds considerably above the posted 45 mph limit in the seconds before the crash.
Armstrong said the airbag control module (ACM) records a short pre-impact window and that the Mazda’s ACM showed roughly 60 miles per hour five seconds before the recorded event and about 42 miles per hour at the recorded point of impact. "It shows... 42 miles per hour," Armstrong testified, adding that the module also recorded braking and that the Mazda slowed to about 18 mph in the seconds before the recorded event.
Armstrong explained that ACM data vary by manufacturer and that not all vehicles provide every parameter; the detective said he obtained an ACM download for the Mazda (Unit 1) but that ACM extraction was not available for Jose Fernandez’s vehicle (Unit 2) because that vehicle’s module was not supported in the department’s system. He described how investigators mark roadway evidence, photograph the scene and use tire marks, paint and an "area of impact" to preserve measurements for later analysis.
The detective confirmed he interviewed the Mazda’s driver, identified in court as Simon Garza, and that his body-worn camera recording of that interview was admitted into evidence. Armstrong said Garza’s statements shortly after the crash varied—initially indicating a red light and later saying he was unsure—and that the body-worn footage and ACM data together helped investigators reconstruct vehicle behavior in the moments leading up to the collision.
The court admitted body-worn and surveillance video exhibits over limited objections and scheduled further testimony, including a medical examiner who may be called at a subsequent session.
