An Alabama man killed by a K-9 officer was one of thousands of Americans bitten by police dogs every year.

Police dog bites are rarely fatal. But in other ways, the case of Joseph Pettaway is not unusual. These dogs, whose jaws and teeth are strong enough to punch through sheet metal, often produce severe injuries. Police employ them not only in emergencies, but also for low-level, non-violent incidents. And there is little oversight, nationally or in the states, of how police departments use them.

These are some of the findings of an investigation by The Marshall Project, with AL.com, IndyStar and the Invisible Institute in Chicago. We obtained dog-bite data from police departments around the country, including the agencies in the 20 largest U.S. cities. Our reporters also examined more than 140 serious cases nationwide, and reviewed thousands of pages of documents, including excessive force lawsuits, department policies, arrest reports and medical studies.

Many people bitten were unarmed, accused of non-violent crimes or weren't suspects at all. Court records show cases often start as minor incidents—a problem with a license plate, a claim of public urination, a man looking for a lost cat. Although some departments now have strict criteria about when dogs can bite, many continue to give officers wide discretion.

Men are the most common targets of police dog bites—and studies suggest that in some places, victims have been disproportionately Black. Investigations into the police department in Ferguson, Missouri, and the Los Angeles County Sheriff’s Department have both found that dogs bit non-White people almost exclusively. Police dog bites sent roughly 3,600 Americans to emergency rooms every year from 2005 to 2013; almost all were male, and Black men were overrepresented.

Read the full article about police dogs by Abbie Vansickle at The Marshall Project.