It happened in 2012 after the horrible mass shooting at Sandy Hook Elementary School in Newtown, Connecticut. The perpetrator was a man named Adam Lanza, who killed himself post-rampage. Initially, his brother Ryan was mistakenly identified as the shooter, as Adam had stolen his brother's ID and had it on him when his body was discovered. The media eventually realized and admitted their error, but in the social media age, bullshit travels faster than the speed of light. That means that since Ryan had been accused of mass murder for more than 1/64 of a nanosecond, the virtual lynch mob had more than enough opportunity to seek his head.
But the Internet didn't simply settle on ruining the day of an innocent guy whose life had already been ruined. They dug into Ryan's profile and found that he had "liked" Mass Effect, a video game they were pretty sure had guns, probably. Never mind that said guns were laser blasters shot at aliens in goddamned outer space, and never mind that the average Facebook user clicks "like" on all sorts of random bullshit. For an angry mob out to blame anybody but the shooter for all the shooting, this was more than enough evidence. Dozens stormed Mass Effect's Facebook page and bombarded it with angry, threatening messages, repeatedly accusing its creators of aiding and abetting a child murderer.