In his upcoming tell-all memoir, Prince Harry is going to reveal something significant.

According to The Sun, the Duke of Sussex is investigating the death of his late mother, Princess Diana.

The Princess of Wales died on August 31, 1997, from injuries received in a horrific vehicle accident in Paris.

Now, French officials believe that Prince Harry has asked them to provide details of the disaster to him so that he may include them in his explosive book.

An source told the magazine that there have been approaches indicating that Prince William's younger brother is very interested in learning more about Princess Diana's death.

After all, many people in France remembered the night of the tragedy, and it's only natural for her son to learn more about the tragic catastrophe in order to include it in his book.

Several royal analysts believe the book would mostly focus on Prince Harry's pain following his mother's death, since he notoriously blamed the tragedy for mental health issues that he attempted to overcome with drinking and substance addiction.

Though it is still unknown what Prince Harry is looking for, there are various mysteries surrounding her untimely demise to investigate.

Princess Diana told her bodyguard that she was frightened she might be slain as well.

According to ex-bodyguard Lee Sansum, she witnessed Princess Diana in tears after learning that her friend, Gianni Versace, had been killed.

"She told me she was afraid she might be killed one day. She inquired whether I felt his murder outside his home was premeditated. I assumed it was."

READ ALSO: Prince Harry Memoir: 8 Shocking Revelations Duke May Talk About In Upcoming Book

Release of Prince Harry's Memoir

Prince Harry's autobiography may have met a hitch.

After it was disclosed last year that he had a $20 million book contract with Penguin Random House, the memoir was set to be released in the fall of this year.

However, speculations circulated that the memoir's release would be postponed since the publishing business neglected to include it in their next lineup.

According to a source, if Prince Harry's memoir is released this year as planned, it should be on Penguin Random House's marketing and PR list "unless they're preparing a surprise or there's been a delay."

Fans should not expect criticism of Queen Elizabeth II in Prince Harry's book, which will instead focus on Prince Charles, Prince William, and how his life wife was a member of the royal family before Megxit.

READ MORE: Princess Diana Death Could've Been Prevented, Former Bodyguard Says