Police and prosecutors are embracing a powerful new tool for taking the he-said, she-said out of hard-to-prove domestic violence cases.

Body cameras worn by police officers record the fear, the blood and the bruises immediately following an assault, and let jurors witness the chaos officers encounter when they arrive at a domestic violence scene. In cities like Columbia Heights and Burnsville, where police routinely wear them, the footage is increasingly being used in court to back up domestic assault charges, even when a victim grows hesitant.

“When the cops are called and come through the door, the victim is very happy and relieved to see them,” said Elliot Knetsch, prosecutor for the city of Burnsville. “They feel safe. They tell the officer what happened. That statement given right at that moment is more likely to be the truth than what comes out even half an hour later, when the implications of what has happened start to set in.”

But the use of body cameras for law enforcement comes with complications. Minnesota legislators looking at regulating their use must balance three crucial concerns — fighting crime, keeping police accountable and protecting privacy.

Even as prosecutors hail the potent videos’ role in prosecuting abusers, advocates for domestic violence victims caution that they also hold the potential to hurt the women the criminal justice system is trying to protect if they find their way into circulation beyond law enforcement uses. And the idea of police recording in homes sets off alarms for privacy advocates.

“It is very difficult to chart a wise course through those waters,” Knetsch said.

Body cameras, in some form, are being used by dozens of police departments in the state.

In the six months since Burnsville police launched a full deployment of body cameras, Knetsch had video for almost every domestic assault case. Burnsville prosecutes about 150 misdemeanor and gross-misdemeanor domestic assaults each year.

Phil Prokopowicz, chief deputy in the Dakota County attorney’s office, agrees that such footage has prosecution value. “It can be influential in resolving the case in terms of negotiations,” he said. “The defendant gets to see the act and know what will be displayed in front of the jury. The documenting of those first moments is very critical to those types of cases, as well as any admissions that may occur as officers are entering.”

‘In the infant stage’

Cameras have been part of police work for decades. They’re mounted on squad car dashboards, in police interrogation rooms, on street corners. Now, bystanders pull out smartphones to record police encounters.

But body cameras add a new wrinkle: They record in homes, and they record officers’ close encounters with victims and perpetrators.

According to a 2015 Minnesota Chiefs of Police Association survey, 41 departments in the state have at least some body cameras, and 70 percent of the chiefs who responded said they generally favor them.

“We have had insights into crime scenes before. As things evolve, this is the next opportunity, but we are in the infant stage,” said prosecutor Paul Young, a criminal division chief in the Anoka County attorney’s office. “I hope the Legislature is speaking with a broad spectrum of people.”

In Columbia Heights, police officers and community service officers wear body cameras and are required to turn them on for enforcement actions and calls for service, which accounts for nearly all of the department’s contact with the public, said Chief Scott Nadeau.

A desire for transparency and accountability drove the rollout, Nadeau said, but body cameras also quickly became valuable investigative tools.

Evidence that endures

On April 3, Columbia Heights police body cameras recorded a woman moments after she was choked so hard she was spitting blood. The defendant tried to prevent the victim from speaking to officers, but body cameras recorded the woman whispering the details of the assault.

It also captured the combative suspect, who threatened to beat the woman until she was unrecognizable, according to the complaint.

“Afterward, she didn’t want to give us a taped statement. She didn’t want to let us photograph the injuries,” Nadeau said. “This gives us an opportunity to capture that evidence in a way we never could before.”

The defendant has been charged with felony domestic assault by strangulation.

Such video takes pressure off witnesses and victims, who often are emotionally and financially tied to assailants and may feel pressure to minimize or recant.

“The emotions of the moment, the family and financial structures makes these cases unique,” Prokopowicz said. “It’s not uncommon for victims to recant or revise their statements.”

What if data go public?

Rebekah Moses, public policy manager for Minnesota Coalition for Battered Women, said she too believes that body cameras can be useful. Video of a violent attack is hard for jurors and others to dismiss, she said.

But Moses said prosecutors also need to work with victims and carefully consider their concerns. For many, there is fear about what will become of that raw video taken after an assault.

“What happens with that data?” she asked. “Will it find its way into a tweet? … Will it unintentionally become a tool perpetrators use to abuse? Everyone is struggling with the same issues.”

Under Minnesota law, such videos are presumed public, but so far no one has requested one from his city, Burnsville’s Knetsch said.

The American Civil Liberties Union of Minnesota supports body cameras to record officers’ interactions with the public except when an officer enters a home in a nonemergency situation. Then, the ACLU argues, homeowners should be able to request that a camera be turned off.

“We recognize this footage will be used in prosecutions,” said ACLU-MN legal director Teresa Nelson. “I would hate to see this invasive tool be used simply to collect evidence. I bristle at that. The only way to justify the intrusion into private homes is the potential to enhance police accountability.”