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The Washington Post published a short documentary in December about an incident involving Desmond Marrow, a former NFL player who was choked by an officer during a confrontation in McDonough, Ga. A cellphone video of the exchange went viral, and our story explored how that experience affects a person’s life.

A new development in Marrow’s case occurred in March, partly because of the footage captured on body and dashboard cameras used by the officers involved in the incident.

The Henry County district attorney’s office decided to bring battery charges against the former officer seen choking Marrow. In the dash-cam video, the officer is heard admitting to choking Marrow and describing to a colleague his intention to leave mention of the choking out of the police report. The Post obtained the dash-cam video and updated the documentary to include the footage.

The new turn in the story raises the question of how effective body and dash cameras are in policing. Following the 2014 shooting death of Michael Brown in Ferguson, Mo., and other widely covered stories about police use of force, public calls for the use of body cameras increased and many police departments across the country began using the technology. Around the same time, in 2015, George Mason University’s Center for Evidence-Based Crime Policy started what is now the largest and most comprehensive review of body-camera use, and the center published its work in March.

Although circumstances, such as Marrow’s, may change because of video evidence, that isn’t always the case. The research shows that the argument on body cameras is complex. “There’s still so much that we don’t know about body-worn cameras and its impact on both the police organization and also police community relationships,” said Cynthia Lum, director of the center and a former Baltimore police officer.

Desmond Marrow is trying to move on from being a part of a viral police arrest video. But the video has shaped who he has become and what he stands for. (Rhonda Colvin, Malcolm Cook, Osman Malik, Jayne Orenstein/The Washington Post)

The study’s main findings note that, although officers and the public support the use of body cameras, they “have not had statistically significant or consistent effects on most measures of officer and citizen behavior or citizens’ views of police. Expectations and concerns surrounding body-worn cameras among police leaders and citizens have not yet been realized by and large in the ways anticipated by each.”

There was one consistent finding: “Body-worn cameras are linked to a reduction in citizen complaints,” said Lum, adding that more research was needed to determine why.

Lum explained the research reveals a disconnect between how citizens and members of law enforcement view such cameras. On the one hand, citizens “believed that cameras could protect them from police misbehavior or excessive use of force or rudeness, or what have you,” Lum said. “And officers, I think, believe that body-worn cameras protect them, them being the police, from frivolous complaints, unfounded complaints.”

Overall, the study suggests that there are no easy answers that can decisively show that an increase in body-camera use has prompted widespread changes in policing. Lum says it’s because the issue is far deeper than a simple fix. She said that the questions raised by Brown’s death and that of Freddie Gray, who died of spinal injuries he suffered while in police custody in Baltimore in 2015, for example, “get at the heart of the relationship between American police and people. Can technology be a panacea to that?"

Lam said: “I’m skeptical of that because I think what strengthens that relationship is much more. We cannot just rely on some technology in hopes that that’ll make that happen. There’s much more to it.”