That sad episode provided many tragically comic and comically tragic examples of that kind of thinking. The New York Times struggle with the shooter's pedigree that eventually preserved the narrative with "White Hispanic". NBC editing the 911 call audio to achieve the desired impact. ABC 're-digitizing" photos to the same purpose. Presidential musings on what his male issue might have looked like. The raising of sweatshirts and Skittles to protest totems. The usual uplifting commentary from the Rev. Al Sharpton. Spike Lee tweeting (incorrectly) George Zimmerman's home address. Zimmerman auctioning his gun to the skinhead community. It was a true Bonfire of the Vanities moment.
Ultimately, the presumption of innocence triumphed over the forces arrayed against it; but it was a near-run thing.