According to a report by The Wall Street Journal, Michael reportedly sold those photos to the National Enquirer, which then published a controversial story about Lauren and Bezos' affair early last year.
"Federal prosecutors in Manhattan have evidence indicating Jeff Bezos' girlfriend provided text messages to her brother that he then sold to the National Enquirer for its article about the Amazon.com Inc. founder's affair, according to people familiar with the matter," the WSJ reported.
The sensational claim came after Bezos visited India with his girlfriend and the photos of the couple in front of Taj Mahal in Agra went viral on social media platforms.
Bezos in February last year accused the publisher of National Enquirer, an American tabloid published by American Media Inc. (AMI), of "blackmail" and "extortion".
Bezos, who is also the owner of The Washington Post, revealed the explosive details in a post on the blogging platform Medium.
"Rather than capitulate to extortion and blackmail, I've decided to publish exactly what they sent me, despite the personal cost and embarrassment they threaten," Bezos wrote in the post while saying that the "top people" at the National Enquirer were responsible for the extortion and blackmail.
Bezos' affair returned to news this week when The Guardian reported that it was "highly probable" that Saudi Arabia hacked Bezos' phone in May 2018, which the Saudi government has denied.
"It seems likely that Michael Sanchez is the primary source for the National Enquirer's story. It's also possible that Saudi Arabia may have hacked Bezos' phone, though that's not a certainty," reports The Verge.
To find out how the Enquirer obtained his intimate texts to Sanchez, Bezos engaged private investigators led by security consultant Gavin de Becker.
After the investigation was initiated, AMI, Bezos alleged, threatened to release more intimate photos and texts.
"In the AMI letters I'm making public, you will see the precise details of their extortionate proposal: They will publish the personal photos unless Gavin de Becker and I make the specific false public statement to the press that we 'have no knowledge or basis for suggesting that AMI's coverage was politically motivated or influenced by political forces'," Bezos wrote.
In the fresh controversy related to her girlfriend, Bezos is yet to issue a statement.
( With inputs from IANS )