Pressure is mounting on Saudi authorities over the killing of Jamal Khashoggi and the case’s aftermath this week as a deadline for action imposed on President Donald Trump by the US lawmakers last year passed without any response from the White House.

A series of rapid-fire developments showed continuing outrage over the murder and dismemberment of The Washington Post columnist at the hands of Saudi spies and security officials dispatched to the Istanbul consulate more than four months ago.

A deadline demanding a response on a US Global Magnitsky Act ruling calling for punishment of state human rights abuses came and went this week without a response from the White House on the culpability of Saudi Crown Prince Mohammad bin Salman, who has strong ties to Mr Trump and his family. The White House says it is conferring with lawmakers, and contiuing to examine the murder.

Hatice Cengiz in Istanbul on Friday introduced a new book about her late fiancee Jamal Khashoggi (AP)

But if the Trump administration and its allies in Riyadh were hoping the 2 October killing would fade away, they were wrong. The case exploded into headlines again this week with a report describing the preliminary result of a UN probe, leaks of classified intelligence tying the crown prince, or MBS as he is known, to the murder, and new proposed Senate sanctions on Saudi Arabia, solidifying Khashoggi’s status as a global icon for press freedom and human rights.

“The attention to Jamal Khashoggi has exceeded in length and depth the regular killings of other political critics from the region dramatically,” said Timothy Kaldas, a fellow at the Tahrir Institute for Middle East Policy.

“Unlike many of the other victims of brutal authoritarians like MBS, Khashoggi allowed observers and the public to put a face to the murderous violence often visited upon individuals willing to risk their freedom and even lives to shed light on the wrongdoing of their leaders.”

The UN special rapporteur’s preliminary report late Thursday, which followed a visit to Turkey, sharply condemned Saudi actions before and after the murder. Agnes Callamard, leader of the mission, also told the Associated Press she had been informed of a previously undisclosed 31 January court hearing in the case of 11 unnamed suspects that Saudi Arabia claims it is prosecuting for the murder.

“The evidence presented to us during the mission to Turkey demonstrates a prima facie case that Mr Khashoggi was the victim of a brutal and premeditated killing, planned and perpetrated by officials of the state of Saudi Arabia and others acting under the direction of these state agents,” the report said.

The New York Times published leaks that if confirmed would be among the most convincing pieces of evidence tying Mohammed bin Salman to the murder of Khashoggi. Based on accounts of leaked US intelligence intercepts, the young crown prince had told a close aide a year before Khashoggi’s murder he would like to use “a bullet” against the journalist. Saudi officials say that the killing was ordered by rogue elements.

A group of both Democratic and Republican Party US senators introduced a new bill that if enacted would restrict arms sales to Saudi Arabia as punishment for the killing.

“Seeing as the Trump administration has no intention of insisting on full accountability for Mr Khashoggi’s murderers, it is time for congress to step in and impose real consequences to fundamentally re-examine our relationship with the Kingdom of Saudi Arabia,” said US senator Robert Menendez, a Democrat, said in a statement.

Agnes Callamard (right), UN special rapporteur on executions, stands in front of the Saudi consulate in Istanbul (EPA)

At a bookshop in Istanbul on Friday morning, Hatice Cengiz, the fiancee of the slain journalist, unveiled a new book about his final days. She wept as she described the loss of Khashoggi, and called for UN and US congressional pressure on Saudi Arabia, and offered to meet with Mr Trump if he shifted his stance on the Saudi leadership.

Ankara also upped pressure on Saudi, reiterating its demand for the extradition of the suspects it has named for trial in Istanbul. “After four months, we are still waiting for answers,” Fahrettin Altun, spokesperson for Turkish president Recep Tayyip Erdogan, wrote in a Tweet. “Where is the body? Who ordered the hit? Was there a local collaborator? The world is watching.”

The new developments add pressure onto Saudi Arabia just as Riyadh was attempting to leave the high-profile murder behind and resurrect its grand plans to draw foreign investment into the country, and begin a geopolitical gambit to confront Iran. But Mr Kaldas suggested that crown prince’s reception at the World Economic Forum conference in Davos last month suggested many key global political and economic leaders have already moved on.

“There is a cynical hypocrisy manifested in many western governments choosing to ultimately ignore MBS’ crimes and try to get back to business as usual,” he said.