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.
The request, issued under the Global Magnitsky Human Rights Accountability Act, requires a response within 120 days.
Saudi Arabia has blamed Khashoggi’s death on rogue agents but denied claims that the crown prince had knowledge of the operation.
US media have reported that the CIA believes Mohammed bin Salman ordered the murder.
In an interview on Sunday, Mr Trump told Fox News that he had refused to listen to a recording of Khashoggi’s murder provided by Turkey, calling it “a suffering tape”.