Every year in the United States, police dogs injure thousands of people, biting and maiming bystanders, officers and people suspected of petty crimes. Dogs have served as instruments of violence in incidents dating back to the days of slavery, and as recently as the Black Lives Matter protests. At the same time, police departments love to show off their dogs—at parades or on Twitter, visiting classrooms or posing with a Girl Scout troop. Some K-9s even have their own adorable Instagram accounts.

In our year-long investigation with The Marshall Project, AL.com and the IndyStar, we identified and tracked individual cases, pulling data across the country to compile more than 150 severe incidents. We found that most bite victims were suspected of low-level, non-violent crimes. Almost none of them were armed. The Marshall Project’s nationwide tracker allows readers to sort incidents by state, read descriptions of the attacks and view videos of some of them.

Explore the full resource here.