Investigators are still sifting through thousands of videos and pictures, both amateur and professional, taken at or around the time of the bombing at the Boston Marathon on Monday.
So too are users of websites such as 4chan and Reddit. The social media sites are crowdsourcing the Boston investigation by asking users to post and analyze photos on their own, and then turn that information over to the FBI.
Some aren't too happy with this, likening the effect to vigilantism, or a witch-hunt, that may be implicating innocent people.
We speak with Alfred Hermida, a professor of journalism at the University of British Columbia.