In the frantic race to be the first to identify the Boston bomber, the reputations of some of America's best-known news organisations have suffered a damaging blow.
CNN was the first to take a hit to its credibility after claiming that, in a "dramatic shift", Boston police had arrested a "dark-skinned male". No such arrest had been made but the network ran with the story for more than half an hour. As the FBI issued a denial, the Associated Press, Fox News and the Boston Globe were forced to retract reports a suspect was being held.
Everyone is anxious to solve this crime. Inspired by TV crime-scene investigation dramas, many social media users have become convinced that digital technology offers the tools to trace the killer – and real-life police work has become the new interactive game.
Reddit, the California-based website, has created an entire subsection, "findbostonbombers", devoted to fingering the culprit from video images of the marathon finish line. Among the first to be identified as the potential terrorist was a bearded spectator – dubbed "Blue Robe Guy" – who was deemed to be holding his backpack in a "very strong looking grip". Fevered speculation ensued. Another Reddit user suggested monitoring pictures for spectators with baby buggies. "If you wanted to move two bulky/heavy backpacks without being noticed, the underside of a stroller might be a good place."
On Twitter, another "suspect" was spotted in silhouette on a balcony in a photograph of the first blast. One user claimed it was "the spookiest thing I have ever seen".
It was in this fevered witch hunt atmosphere that CNN's chief reporter John King made his blunder on Wednesday. "I was told by one of these sources, who is a law enforcement official, that this was a dark-skinned male," he told the network's audience.
The problem for the major news organisations is that America's biggest terrorist incident since the Twin Towers demands answers and so far there are none. Twitter and other social media have filled a news vacuum with rumours.
After John F Kennedy was assassinated in 1963, speculation later surrounded "Umbrella Man", a supposedly suspicious character shown in photographs carrying an umbrella. Last night, amid reports police have identified a suspect on CCTV, many amateurs and professionals of modern media were conducting a similar exercise.