Mobile video is changing the way we witness crime, from live footage of a mentally disabled man tortured by four assailants , to a recording that led to the manslaughter conviction of an Israeli soldier , to the body cameras designed to keep police accountable.
We're all still wrestling with the implications.
In theory, such videos should make it easier to hold criminals, including police officers who violate the law, accountable. In practice, that hasn't always worked out the way proponents had hoped, although smartphone video played a big role in elevating public awareness of police violence.
And sometimes the presence of a camera might actually encourage criminal activity, or at least deter bystanders from helping victims.
Scene of the crime
It's not clear how any of that might have played out in an incident on this week, when attackers used Facebook Live to stream the beating and torture of a man with mental health problems. They threatened him with a knife, cut off his clothing and forced him to drink from a toilet.
The assault went on for up to two days, according to police, though it's unclear how much of it was streamed on Facebook Live. Police have arrested four people in connection with the crime.
Last year, an Ohio woman plead not guilty to charges of rape, kidnapping and other crimes for live-streaming the rape of a friend on Periscope, Twitter's live-streaming app. Prosecutors said Marina Lonina continued to film the assault despite the victim's cries for help, caught up in the attention the livestream was getting. Lonina's attorney said she was recording the attack as evidence.
During a Thursday press conference about the Chicago assault - itself live-streamed on Facebook - Chicago Police Cmdr. Kevin Duffin noted, "I can't understand why anyone puts anything on Facebook."
Facebook says it does not allow people to "to celebrate or glorify crimes" on its site. It has already removed the original video of the Chicago incident for that reason.
But the social network does allow crime video when people share it "to condemn violence or raise awareness about it," the company said in an emailed statement.
That can lead to tricky assessments of intent. Facebook, for instance, wrote in a blog post that it would allow a violent video posted by someone who used it to help find the shooter, but would remove it when posted by another person who mocked the victim or celebrated violence.
Facebook generally tries to avoid making such judgments, preferring to rely on algorithms that automatically filter out banned content such as pornography. When it makes exceptions, it often wades into difficult territory - such as the time it was forced to restore the Pulitzer Prize-winning "napalm girl" photo after removing it because it features a naked child, blind to the photo's historical context and significance.
"We understand the unique challenges of live video," Facebook wrote in its July blog post after footage of a dying Philando Castile, bleeding inside a car after he was shot by police, went viral . The social network says it keeps a team on-call 24 hours a day to respond to reports of inappropriate video - though its reactive approach means that some material could easily go unreported.
Facebook Live is an important product for Facebook, and in recent months the company has gone to great lengths to promote it with notifications, sidewalk ad displays and TV commercials. The vast majority of live streams don't involve crime, and Facebook is unlikely to rein back the product just because of a few difficult situations.
It's "unfortunate" that acts of violence and terror have come to represent live streams, said Benjamin Burroughs, a professor at the University of Nevada, Las Vegas focused on emerging media, in an email to The Associated Press.
More civic-minded streaming lets people "bypass traditional media and connect directly with their social networks and the general public," he said. Live streaming is powerful, he added, because it "produces really strong emotions in viewers, which can be used to unify or divide people."
Ready for your close-up
Online crime footage has been around much longer than live streams. While live broadcast gives them a sense of immediacy, many live videos only go viral well after the fact. So it may not really matter whether a video is live or not, just that it's a concrete record of a crime that happened, visible to all who dare to click.
Even then, video evidence doesn't necessarily lead to criminal convictions. In South Carolina, a white police officer was charged with the 2015 shooting of an unarmed black man after a traffic stop. A video shot by a bystander clearly shows Keith Scott being shot eight times in the back. But the jury was unable to reach a verdict and forced a mistrial.
In another case in Ohio, the two sides in the trial clashed over a video from a police officer's body-worn camera that showed him shooting an unarmed man following a traffic stop. That case also ended in mistrial. The officer, Ray Tensing, will be retried.
As for users, a quick trip down memory lane confirms that some people will do almost anything in front of a camera to get online attention. Before Twitter gutted its quirky video-sharing app Vine, a popular phrase among users was "do it for the Vine," the idea that people will do anything - usually weird, comical things - just for the sake of a six-second Vine video.
But it wasn't just fun and games. Fights and violence also found a home on Vine under the hashtag #SmackCam - a 2013 "internet trend" that had people recording and posting videos of themselves hitting people in the face.