The federal government undercounted police killings in the United States by 17,000 over the past 40 years, according to a new study. Research published Thursday in The Lancet compared information on police killings in the National Vital Statistics System to figures in three open-source, grassroots databases: Fatal Encounters, Mapping Police Violence, and The Counted. From 1980 to 2018, police in the U.S. killed 30,800 people, 17,100 more deaths than recorded in the NVSS, the researchers estimated. Additionally, deaths in the U.S. from police violence increased from 25 per 100,000 people in the 1980s to 34 in the 2010s, they said.