In the video, the teen was dressed in a sheet, had a scarf wrapped around his head, made erratic movements while in a crosswalk and pointed the fake weapon at vehicles, prompting motorists to call 911.
"Every one of those people was calling 911 because they had a real concern about it," prosecutor Michael Anderson said in closing arguments Monday at Turley's trial. "It scared them. They don't know if that's real, but it's real enough for them to get the police involved."
Turley pleaded not guilty to charges of endangerment and engaging in a criminal hoax. It took jurors only two hours of deliberations on Monday afternoon before finding Turley guilty.
Anderson said Turley, who was responsible for his nephew's safety that day, could have gotten his young relative killed in the hoax.
Anderson said some motorists who saw the teen with the realistic-looking fake launcher had discussions about whether they should run him over. Still, some recordings of 911 calls also showed that some witnesses assumed the weapon was a fake.
Turley's attorney, Brad Rideout, said callers weren't terrified and instead figured they were witnessing a joke, pointing out that they could see his client filming the hoax and that his nephew did a brief dance while on the street corner.
"This was something that they knew was a hoax right away," Rideout said.
Earlier in the case, Rideout had told jurors that it was foolish for Turley to get his nephew involved but noted that no one was injured and no vehicles wrecked as a result of the hoax.
In testimony last week, Turley said his video of the hoax was meant to be satirical and that most passing motorists laughed at them. He told jurors he didn't think his actions endangered his nephew's life.
In the YouTube video, a narrator identified as Turley said he wanted to see how long it took authorities to respond to a terrorist situation and mentioned a movie theater shooting two weeks earlier that killed 12 people in Aurora, Colo.
The teenager carried the fake launcher on his shoulder as he made his way across a crosswalk. The narrator said the teen wanted to appear as intimidating as possible in hopes that people would call police.
The video also showed the first police officer to arrive on the scene, finding the 16-year-old standing in his uncle's driveway. The officer calmly told the teenager to put down the weapon and Turley to put down the camera.
The officer didn't draw his gun.
Police left the day of the hoax without making any arrests, but Turley was arrested nearly two months later after police interviewed people who called emergency services and later saw the video posted on YouTube.