WASHINGTON (Reuters) - U.S. Defense Secretary James Mattis said on Wednesday the United States has “no smoking gun” that Saudi Crown Prince Mohammed bin Salman was involved in the killing of U.S.-based Saudi journalist Jamal Khashoggi in Istanbul last month.

Asked about reports that a CIA assessment earlier this month concluded the crown prince had ordered Khashoggi’s death, Mattis referred journalists back to the intelligence agency.

“We have no smoking gun the crown prince was involved, not the intelligence community or anyone else. There is no smoking gun,” Mattis told reporters at the Pentagon, adding that the United States still expected those responsible for the killing to be held accountable.