The team, led by investigator Gavin de Becker, believed that Michael Sanchez – the brother of Mr Bezos’s girlfriend, Lauren Sanchez – gave the texts to the tabloid, several media reports have suggested. Mr Sanchez has previously denied he was involved in leaking the material and this weekend he attacked the Amazon founder.
Mr de Becker, who has been in charge of Mr Bezos’s security for two decades, reached the conclusion after the texts were published by the Enquirer last month, and launched a probe to see where the leak had come, according to both the Daily Beastwebsite and the Associated Press news agency.
Last week, Mr Bezos made headlines around the world when he claimed in a blogpost that the Enquirer had threatened to publish explicit photographs of him unless he issued a public statement reversing claims by Mr de Becker that the magazine’s reporting of his private life was politically motivated.
He refused to do so, and instead made public emails between his lawyers and those of American Media Inc (AMI), the parent company of the Enquirer, and whose owner is an ally of Donald Trump. One of the images was said to be a “below the belt selfie”.
“Of course I don’t want personal photos published, but I also won’t participate in their well-known practice of blackmail, political favours, political attacks and corruption. I prefer to stand up, roll this log over and see what crawls out,” Mr Bezos wrote.
The findings added to “the intrigue surrounding the clash between the pro-Trump tabloid and the world’s richest man”, the AP reported.
— Michael Sanchez (@mikey2go)June 22, 2018
It said Mr Trump had been highly critical of Mr Bezos over his ownership of the The Washington Post and Amazon, and the Post’s coverage of the White House.
Mr Sanchez is a supporter of Mr Trump and an acquaintance of Trump allies Roger Stone and Carter Page. He is also the manager of Ms Sanchez, a former TV anchor.
The investigators have not said how they believe Mr Sanchez came into possession of his sister’s intimate messages.
Mr Sanchez did not immediately respond to a message seeking comment. Mr de Becker and Amazon also did not respond to emails.
Over the weekend, Mr Sanchez told Fox News: “Everything that Gavin has advised Jeff to do has only amplified the magnitude of the scandal.”
A lawyer for AMI, Elkan Abramowitz, declined to name who provided the texts but told ABC News it was a reliable source, well-known to Mr Bezos and Ms Sanchez.
She said that the source had provided information to the company for at least seven years.
Mr Sanchez previously told the Post he was not the source of the information. He said the claims about him were “lies, half-truths, sloppy tabloid leaks and crazy conspiracy theories”.