Criminal networks with Latin American roots, such as MS-13 and the 18th Street gang, are using the administration's open-door policy at the border to slip in recruits that are causing a huge spike in murder and violence throughout the nation, according to an immigration expert. Testifying Thursday at a House hearing on the border surge of young Latinos, the expert said, "Established gangs have been able to transfer an unknown number of experienced foot soldiers from Central America to help colonize new criminal territory in the United States." Jessica M. Vaughan, the policy director for the Center for Immigration Studies,...