FILE PHOTO - Special Rapporteur on extrajudicial, summary or arbitrary executions at the Office of the United Nations High Commissioner for Human Rights, Agnes Callamard waits for a news conference to start in San Salvador, El Salvador, February 5, 2018. REUTERS/Jose Cabezas

GENEVA (Reuters) - The U.N. investigator into the killing of Saudi journalist Jamal Khashoggi on Wednesday called on countries to invoke universal jurisdiction for what she called the international crime and make arrests if responsibility of individuals is proven.

Agnes Callamard, U.N. special rapporteur on extrajudicial executions, asked if universal jurisdiction meant potential arrests abroad of suspects, told reporters: “If and when the responsibility of those individuals has been proven, including the responsibilities of a level that warrant arrest, absolutely.”

Callamard also told reporters that she had not been able to substantiate reports that U.S. authorities had intercepted communications from Saudi Crown Prince Mohammed bin Salman on an alleged plot, but said that they should have been investigated and Khashoggi, a U.S. resident, should have been warned.

Judicial authorities in countries that recognize universal jurisdiction for serious offences such as war crimes and torture can investigate and prosecute those crimes no matter where they were committed.