“A police standoff in Randallstown, Md., on Monday in which a 23-year-old woman with a shotgun was killed after the police say she had been encouraged by her online followers to defy their orders has highlighted an unexpected role of social media in violent encounters.” Social media can provide a view into crime scenes. It can also become a part of them. Here’s the NYT’s Daniel Victor on how Instagram posts may have escalated a fatal standoff.