Washington (CNN Business) The explosive forensic analysis that concluded Amazon CEO Jeff Bezos was hacked is coming under scrutiny from independent security experts, some of whom say the evidence isn't strong enough to reach a firm conclusion.

The criticism, including from several high-profile and respected researchers, highlights the limits of a report produced by FTI Consulting, the company Bezos hired to investigate the matter.

But it also underscores the challenges of finding rock-bottom truth in the world of digital forensics, a messy business shaped less by absolute certainties and more by degrees of confidence and calculated probabilities.

The report — a summary of which was released this week by United Nations investigators who vetted it — determined that in May 2018, Bezos's phone received a WhatsApp message from the account of Saudi Crown Prince Mohammed bin Salman, with whom Bezos had used WhatsApp to communicate since at least the previous month. After the message, the report said, Bezos's phone began transferring large amounts of data off of the device. And, according to the report, at least two subsequent messages from the crown prince's account seemed to indicate knowledge of events in Bezos's private life, the report said. The report suggested the incident bore hallmarks of sophisticated hacking software.

Saudi Arabia has denied it was responsible for hacking Bezos's device.

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