Madison school shooting highlights troubling online group ties [Video]

In the months leading up to a school shooting in Madison last December, 15-year-old Natalie Rupnow was openly discussing an attack online, according to court records, before she killed teacher Erin West, student Rubi Vergara, and then turned the gun on herself at Abundant Life Christian School.Police rushed to Abundant Life Christian School last December, responding to yet another tragedy striking a place of learning. Since the attack, investigators and researchers have been digging into Rupnow’s very public online past, piecing together the puzzle of her actions. “She exhibits many of the same behavioral characteristics that we’ve seen in virtually every other mass shooting that’s occurred in the United States over the last 10 years,” John Cohen, a former counterterrorism official at the Department of Homeland Security and now an ABC contributor, said. Cohen now leads a team of researchers at the Center for Internet Security.Social media accounts showed Rupnow …