St. Louis County Prosecutor Robert McCulloch delivered a sometimes combative 25-minute address Monday night to announce a grand jury's decision not to indict Ferguson, M.o, police officer Darren Wilson for the Aug. 9 shooting death of black teenager Michael Brown. During the announcement, McCulloch focused particular attention on the role of social media in covering the story, which he blamed for misleading the public and making the investigation of Brown's death fraught from the start.

McCulloch began the press conference by extending his sympathies to the Brown family. But he quickly lit into the online churn of news and discussion on sites such as Facebook and, especially, Twitter. After Brown's death, the prosecutor said, "within minutes various accounts of the incident began appearing on social media."

And yet, decried McCulloch, those retellings of what had taken place were "filled with speculation, and little, if any solid, accurate information." In fact, the most significant challenge in his three-month investigation, he said, was the insatiable 24-hour news cycle and "non-stop rumors on social media," which he said clung to any available scrap of real or imagined insight into the case.

McCulloch's assessment sparked immediate reaction on, yes, social media:

Social media has been part of the Ferguson case since the very beginning. The protests in Ferguson that followed Brown's death were well-covered online; tweets from the streets by St. Louis Alderman Antonio French made him a household name for a time. The detention of a Washington Post reporter by local police became known via Twitter. In the months since, there has been little let-up around the #Ferguson hashtag. Twitter says that there were more than 3.5 million tweets around the planet mentioning the grand jury's decision in just the three hours after it was released.

McCulloch acknowledged that much of the social media coverage has been fueled by public frustration with the lack of information coming from his office or the police about the investigation. But, he argued, withholding details of the investigation gave them a "yardstick" for figuring out whether eyewitnesses were telling the truth. Some, he said, had simply picked up details -- like Wilson standing over Brown and firing shots into his back -- that were swirling around online.

In fact, again and again, McCulloch slammed the ephemerality of social media and praised the solidity of physical evidence, such as bullet wounds and blood splatters. "Physical evidence does not change because of public pressure or personal agenda," McCulloch said. "Physical evidence does not look away as events unfold. Nor does it block out or add to memory. Physical evidence remains constant and as such is a solid foundation on which cases are built."

And yet, as noted by citing the grand jury records released Monday night by McCulloch's office, "the medical investigator did not take photographs at the scene of Brown's death because the camera battery had died." It is those sorts of failings that have made some people believe that more eyes parsing the process -- even if they aren't privy to every bit of evidence -- are necessary.

McCulloch seemed to agree that there should be sustained, even obsessive, attention on a case like this, even as he went after social media. "For how many years have we been talking about the issues that lead to incidents like this," McCulloch concluded, "and yet after a period of time, it just sort of fades away?" The prosecutor encouraged everyone involved in the Ferguson conversation "not to let that go."

Of course, not letting things go is exactly what social media has proven, in Ferguson and elsewhere, to do exceptionally well.