A former senior Syrian security official has told the FBI that American freelance journalist Austin Tice was killed in 2013 on the orders of President Bashar al-Assad, an account that has not been corroborated by the United States but marks the first time a senior official in the Assad regime has spoken to U.S. officials about Tice’s fate. The U.S. government is investigating the claims made by Bassam al-Hassan, a member of Assad’s inner circle and his adviser for strategic affairs,...