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RTI Stories

Violence, Traffic Stops, and Deaths in Police Custody: Criminology Research at RTI

"We found that individuals with mental illness are at high risk of victimization"

In the 2010's, RTI was especially active in crime and policing research. In 2014, researchers at the Institute—in conjunction with colleagues at North Carolina State University, Duke University, Simon Fraser University, and the University of California, Davis--examined the link between violence and mental illness and found that, contrary to popular belief, adults with mental illness are significantly more likely to be victims than perpetrators of violence.

The research team found that nearly 31 percent of the study's 4,480 participants had been victimized in the six months prior to being interviewed, while less than 24 percent had committed acts of violence. Of the violent acts committed by adults with mental illness, the majority— just under 64 percent—were committed in residential settings, not in public. "We found that individuals with mental illness are at high risk of victimization, representing a substantial public health concern," said Richard Van Dorn, the study’s coauthor.

In 2015, law-enforcement agencies in the United States were facing increased scrutiny, both internal and external, related to potential racial bias in their policing activities. For example, the Durham, North Carolina police department took steps to better understand the basis for accusations of racial bias related to their policing practices, turning to RTI to use scientifically rigorous methods to look for patterns of racial disproportionality in traffic stops.

RTI researchers analyzed more than 150,000 traffic stops that had been conducted by the Durham Police Department over a six-year period—focusing on stops that occurred during the intertwilight period, between 5 p.m. and 9 p.m., when it is light during some months and dark during other months. The results did indeed uncover a pattern of racial disproportionality: specifically, when the police stopped male drivers, the odds of the driver being black were 20 percent higher in the daylight, when the race and sex of the driver were easier to see.

Addressing another issue of national concern, RTI researchers found that an estimated 1,900 people died in the United States in the course of being arrested or while in police custody, from June 2015 through May 2016. This count included persons who died during the arrest process, including justifiable homicides by law enforcement personnel, as well as deaths attributed to suicide, accidental injury, and natural causes.

"The redesigned arrest-related deaths program combines information from media sources, law-enforcement agencies, medical examiners, and coroner's offices to both identify and confirm arrest-related deaths," said Duren Banks, senior research criminologist at RTI. "This mixed method approach results in a more complete picture of the scope of arrest-related deaths in the U.S."