Crown Prince Mohammed bin Salman of Saudi Arabia in Buenos Aires in November. (Sergio Moraes/Reuters)

THE PUBLICLY available evidence that Saudi Crown Prince Mohammed bin Salman bears responsibility for the murder of Post contributing columnist Jamal Khashoggi continues to mount. The latest piece is a 2017 conversation between the crown prince and a key aide in which he vowed to use “a bullet” to stop Khashoggi if he did not agree to return to the kingdom and stop criticizing the regime. That chilling statement, reported by the New York Times, was intercepted by U.S. intelligence agencies, which means it probably forms part of the basis for the Central Intelligence Agency’s judgment that Mohammed bin Salman ordered the attack against Mr. Khashoggi in Turkey last Oct. 2.

There is much other incriminating data. Saudi authorities have acknowledged that the operation was organized and overseen by two of the crown prince’s closest aides, including Saud al-Qahtani. The Times reported that the prince had previously dismissed warnings from Mr. Qahtani that an operation against Mr. Khashoggi could cause an international uproar. U.S. intelligence also found that the two men exchanged numerous text messages immediately before and after the killing, according to the Wall Street Journal. And the team that traveled to the Saudi Consulate in Istanbul included several members of Mohammed bin Salman’s personal bodyguard.

The U.S. Senate drew the obvious conclusion in December when it unanimously adopted a resolution holding the crown prince responsible for the death of Mr. Khashoggi, who was also a legal U.S. resident. Yet the Trump administration continues to deny the facts and the legal mandate to act on them. On Friday, in response to a formal inquiry from members of the Senate Foreign Relations Committee, the White House declined to issue a determination on the culpability of Mohammed bin Salman. “The president maintains his discretion to decline to act on congressional committee requests when appropriate,” CNN quoted an official as saying.

Congress should not accept that response. Under the Global Magnitsky Act, a law governing the punishment of human rights abuses, the administration is required to respond to congressional inquiries about crimes such as the Khashoggi murder by identifying and sanctioning those responsible. The White House last year announced sanctions against 17 people for their roles in the killing, including Mr. Qahtani. But it was separately tasked by then-Sen. Bob Corker (R-Tenn.) and Sen. Robert Menendez (D-N.J.) with determining Mohammed bin Salman’s responsibility under the law. The deadline for replying was Friday.

The non-answer is a blatant dodge that ignores the finding of the CIA and the abundant evidence behind it. It makes a mockery of the Magnitsky law, as well as of U.S. principles by covering for the crown prince to protect the cozy relations between him and President Trump, as well as Mr. Trump’s son-in-law, Jared Kushner. The president has repeatedly justified the relationship by citing overblown Saudi promises to purchase weapons from the United States — which only makes the moral corruption of his position more pungent.

The Saudi show of accountability for the Khashoggi murder has been a travesty — a closed trial of 11 unidentified suspects, apparently not including Mr. Qahtani or any other senior figure. Now, the Trump administration, which claims to be seeking justice, has once again made it clear that it will not pursue it. That leaves Congress. The Senate as well as the House must return to the question of Mohammed bin Salman’s responsibility — and ensure that consequences follow its conclusion.