Lack of sound in Chicago police videos raises more questions

CHICAGO (AP) — A police dash-cam video that captures a white Chicago officer fatally shooting a black teenager 16 times has no sound, nor do videos from four other squad cars at the scene.

The silence is almost sure to figure into the ongoing federal investigation of the case, and it raises questions about whether officers were careless with the recording equipment or, worse, attempting a cover-up.

Several experts on the type of equipment commonly installed in police vehicles told The Associated Press that it's plausible for a single squad car to have a glitch preventing sound recording.

The silent video at the core of the shooting case in Chicago shows officer Jason Van Dyke stepping out of his car on Oct. 20, 2014, and almost immediately opening fire on Laquan McDonald as he walks away from officers.

On the same day that the video was released last week by the city, the Cook County State's Attorney's Office charged Van Dyke with first-degree murder.

Sound can be central to understanding what happened at a crime scene, said Ed Primeau, a Michigan-based audio and video forensics expert.

In an email to The Associated Press, he wrote: "As with any technology, at times software issues or operator error may keep the cameras from operating as they normally should."

Primeau said it's likely that federal authorities would bring in forensics experts to determine why no useable audio seems to exist, with other investigators probably reviewing logs for any notes about how the systems were operating before and after the shooting.