President Trump used the death of Mollie Tibbetts on Wednesday to call for a change in immigration laws and justify his separation of illegal immigrants from their children at the border. Trump tweeted a video message about Tibbetts — who was allegedly murdered by an illegal immigrant in Brooklyn, Iowa — just one day after two of his close associates were convicted of federal crimes. “Mollie Tibbetts, an incredible young woman, is now permanently separated from her family,” Trump said in a reference to his administration’s family separation policy. “A person came in from Mexico illegally and killed her.” The...