During the active crisis of the Parkland school shooting in February 2018, a photo misidentifying the alleged perpetrator moved from 4chan to the mainstream media when Infowars picked up the image, muddying the waters around the actual shooting. The misidentification led to targeted harassment of the individual in the photograph, who was not associated with the shooting.
STAGE 1: Manipulation Campaign Planning and Origins
On February 14, 2018, Nikolas Cruz began his attack on Marjory Stoneman Douglas High School at 2:19 p.m. (ET). The first 911 call was placed at 2:22 p.m. Officers were dispatched to the school, and the shooter was identified as a “white male” by police dispatch at 2:28 p.m. News of a shooting broke online and many flocked to social media for information on the breaking news. The gender and race of the shooter was of great interest to many, specifically to far right extremists aggregating information in various forums and websites, specifically 4chan and 8chan’s “Politically Incorrect” boards (/pol/). There were many threads discussing the shooting on the /pol/s throughout the day. It was on these boards that a small group of anonymous operators seeded a campaign misidentifying an unrelated individual as the suspected shooter.
[…]
Source: Misidentification: Parkland Shooter | Media Manipulation Casebook