Police Jailed A man For Murder, Algorithm Was Key Evidence

CHICAGO (AP) — Michael Williams’ wife pleaded with him to remember their fishing trips with the grandchildren, how he used to braid her hair, anything to jar him back to his world outside the concrete walls of Cook County Jail.

His three daily calls to her had become a lifeline, but when they dwindled to only a few a week, the 65-year-old felt he couldn’t go on. He made plans to take his life with a stockpiled stash of pills.

Williams was arrested last August, accused of murdering a young man from the neighborhood who asked him for a ride during a night of unrest over police brutality. The key evidence came from video of a car driving through an intersection, and a loud bang picked up by acoustic sensors. Prosecutors said audio technology powered by a secret algorithm indicated Williams shot and killed the man inside his car.

“I kept trying to figure out, how can they get away with using the technology like that against me?” said Williams. “That’s not fair.”

Williams was jailed for nearly a year before prosecutors, citing insufficient evidence, asked a judge to dismiss the case.

Williams’ experience highlights the real-world impacts of society’s growing reliance on algorithms to help make consequential decisions about public life. This is especially apparent in law enforcement, which has turned to technology like acoustic gunshot detection. One such firm, ShotSpotter, says its evidence has increasingly been admitted in courtrooms, now some 200. ShotSpotter’s website says it’s a leader in policing technology solutions that helps stop gun violence by using algorithms to classify 14 million sounds as gunshots or something else.

But an Associated Press investigation, based on thousands of internal documents, emails and confidential contracts, along with dozens of...