A Chattanooga woman grabbed her cellphone and used it to record a fight that broke out in College Hill Courts on Monday night.
Now the video is critical evidence as police investigate the slaying of 15-year-old Shaviya Vinson, who reports say was stabbed to death with a pair of scissors during the brawl.
It's the second time in four months investigators have recovered video related to a killing taken by a bystander's cellphone camera.
Wide access to cellphone cameras means more violent outbursts such as street fights are documented, said Chattanooga Police Assistant Chief Tim Carroll.
"We've already got video in patrol cars, banks, gas stations," Carroll said. "On phones now, the [camera] quality is high-definition, and everyone has them hooked onto their belts."
The police department has a tech specialist who can upload photos and video from any kind of cellphone, said Carroll.
The woman recorded less than a minute of Monday's fight, but investigators say the video powerfully illustrates the events leading up to Vinson's death.
"If a picture's worth a thousand words, a video is worth much more than that," Carroll said.
Police have charged Temekia Deshon Reed with criminal homicide, attempted first-degree murder and aggravated assault in connection with Vinson's death.
In September, Hamilton County District Attorney Bill Cox used an iPad to show a judge a cellphone video depicting a street fight and shooting that killed 19-year-old Aundre Bush.
The woman accused in the stabbing, Lathe Corbin, 30, was identified in the video holding a handgun and pointing it at Bush.
Cox said using video of any kind makes a powerful impression.
"When a crime is recorded on video -- obviously that's good evidence," Cox said.
Corbin's next appearance in Hamilton County Criminal Court is set for January.
The people who recorded the videos of the Bush and Vinson homicides turned them over voluntarily.
But Carroll said investigators could probably use warrants and subpoenas to obtain such video evidence if they believe it exists.