Body camera footage made headlines again this week after Officer Ray Tensing was indicited for murder after he allegedly shot a man in the head during a traffic stop.

At a news conference, prosecutor Joseph Deters said the footage was "shocking" and cited it as a key component in the evidence that lead a grand jury to indict tensing.

While Tensing's case shows how body cameras can shed light on an incident, experts say how the cameras will affect officers and police departments on a large scale remains largely unknown.

Michael Broder, a therapist who worked with the Philadelphia police department for five years providing psychological counseling, said the big question among experts is if the body cameras will make police afraid to act or if they will just not act inappropriately.

“Some cops are going to welcome it and some cops who are not going to [care] and there other cops who are going to make a decision, ‘I’m not going to take any chances for losing my job,’... or go to jail,” for a single action, said Broder. “The independent variable there is the rise in crime statistics or whether that it rises at all.”

There are not many studies on the effects of body cameras, but one important one found that use of force and complaints against police went down after the technology was introduced in a small California town. In the 2014 study, researchers from the University of Cambridge’s Institute of Criminology studied police officers in the town of Rialto, California who had been given body cameras.

“Knowledge that events are being recorded creates ‘self-awareness’ in all participants during police interactions,” said University of Cambridge officials in a statement on the study. “ This is the critical component that turns body-worn video into a ‘preventative treatment.’”

They said the camera may cause individuals to modify their behavior in response to a “third-parry” surveillance related to the camera. They compared the camera to a proxy for a “legal courts — as well as courts of public opinion” that lead officers to be more cautious.

"An officer is obliged to issue a warning from the start that an encounter is being filmed," explained study author Barak Ariel in a statement. "Impacting the psyche of all involved by conveying a straightforward, pragmatic message: we are all being watched, videotaped and expected to follow the rules."

According to the study, complaints against officers in the area dropped from 0.7 to 0.07 per 1,000 contacts in that year-long study.

Another study looked at how surveillance cameras can increase accountability among bystanders in an emergency. The “bystander effect” has been used by social scientists to explain why people are less likely to help when they’re in a group than when they’re alone.

In part researchers have found that people may be less likely to help when they think someone else can take on those duties. However, in the 2012 study researchers found by adding a camera, participants had more “public self-awareness” and as a result were more likely to act and help.

David Silber, a professor of psychology emeritus at George Washington University and expert in the psychology of crime and violence, said more study was needed to understand how body cameras will affect police but he suspects they aren’t going anywhere soon.

“I have a feeling whatever the influence of body cameras are now they will tend to grow as it becomes known they are pretty reliable records and subject to some interpretation of course,” said Silber.