US President Donald Trump has been asked to ascertain whether Saudi Crown Prince Mohammed bin Salman played a role in the murder of Jamal Khashoggi.
Republican and Democratic leaders of the US Senate Foreign Relations Committee on Tuesday sent a letter demanding a second investigation.
Mr Trump earlier defended US ties with Saudi Arabia despite international condemnation over the incident.
Khashoggi was killed on 2 October inside the Saudi consulate in Istanbul.
In a statement on Tuesday, Mr Trump acknowledged that the crown prince "could very well" have known about Khashoggi's brutal murder, adding: "Maybe he did and maybe he didn't!"
He later stated that the CIA had not made a "100%" determination on the killing.
Following the president's comments, Republican Senator Bob Corker and Democrat Bob Menendez issued a statement on behalf of the Senate Foreign Relations Committee.
In it they called on Mr Trump to focus a second investigation specifically on the crown prince so as to "determine whether a foreign person is responsible for an extrajudicial killing, torture or other gross violation" of human rights.