In a day of dramatic developments that threatened to deepen the crisis for Saudi Arabia, the United Nations rapporteurs released details of advanced technical analysis that established "grounds for a reasonable belief" that Bezos was the victim of "intrusive surveillance via hacking of his phone as a result of actions attributable to the WhatsApp account used by Crown Prince Mohammed bin Salman".
Callamard, the special rapporteur for extra-judicial killings, and Kaye, special rapporteur for free expression, said in a statement that they believed the hack was carried out "in an effort to influence, if not silence, The Washington Post's reporting on Saudi Arabia" and called for an "immediate investigation by U.S. and other relevant authorities".
Officials at the Saudi Embassy in the USA have called the latest allegations related to Bezos "absurd" and called for further investigation into what happened.
But the independent United Nations experts - Agnes Callamard, special rapporteur on summary executions and extrajudicial killings, and David Kaye, special rapporteur on freedom of expression - said the crown prince's "possible involvement" had to be investigated.
It's claimed that the Saudis targeted the world's richest man Bezos because of his ownership of the Washington Post, whose columnist Jamal Khashoggi wrote in highly critical terms of the crown prince.
Mendelsohn, who helps run Facebook's Europe, Middle East and Africa business, said that the company would take any allegations that its service was used in a hack very seriously and would look into it, but said the company couldn't "comment on any individual story".
The report, a copy of which was first published by Motherboard, said that within hours of receiving the video file there was "an anomalous and extreme change" in the device's behavior, with the level of outgoing data from the phone jumping almost 300-fold.
Callamard said she had previously stopped short of making determinations about the precise nature of Prince Mohammed's involvement in the Khashoggi murder.
But de Becker did not specify which part of the Saudi government he was blamed for the hack and gave few details about the investigation that led him to the conclusion that the kingdom was responsible.
"We call for an investigation on these claims so that we can have all the facts out".
The hashtag, say experts, is a variation on anti-Amazon tags shared off and on by Saudi users since Jeff Bezos first raised questions last February about the kingdom's connection to a National Enquirer article featuring intimate texts between him and a woman with whom he was having an affair.
"Our investigation learned of at least 2 instances in which texts sent to Bezos from MBS" WhatsApp account may reveal awareness of private information that was not known publicly at the time. Pecker is also a close ally of Trump.
The kingdom denies the prince was involved in the killing and the court cleared his former top aide.
Saudi Arabia has promoted a veneration of the crown prince in an effort to swing nationalist opinion behind his reforms, which have been accompanied by a crackdown on dissent at home.
NSO denied the claims in the lawsuit and said it would "vigorously fight them".
Citizen Lab concluded with a "high degree of confidence" that Saudi Arabia was the ultimate party behind the hack.
Amnesty International will ask an Israeli court on Thursday to order Israel to revoke the export licence of NSO Group, whose software is alleged to have been used by governments to spy on journalists and dissidents.
Sophisticated mobile spyware - such as a package called Pegasus, made by the Israeli hacker-for-hire company NSO Group - is created to bypass detection and mask its activity.
Almasarir is a human rights activist and satirist who regularly pokes fun at the Saudi royal family and, in particular, the crown prince.
Within an hour, "massive and unprecedented exfiltration of data" happened from Bezos' phone.
"Recent media reports that suggest the Kingdom is behind a hacking of Jeff Bezos' phone are absurd".