Extremist posts by an account on Russian social media that has been linked to the suspect in the Texas mall shooting have sparked an online debate about the motivation for the attack. Mauricio Garcia, 33, was named by authorities as having carried out the shooting on Saturday in Allen, a suburb northeast of Dallas, Texas, which left eight people dead and several others injured. Online researchers have since identified an account on OK.ru, believed to belong to the suspect, which shows tattoos of Nazi imagery and expresses a fascination with mass shootings. Some hate watchdogs have said that the posts...