Cawthorne then suggests that "another black box" could have been dropped off the coast of Australia to divert the efforts of search teams. "After all, no wreckage has been found in the south Indian Ocean, which in itself is suspicious," he wrote.
Irene Burrows, whose son and daughter-in-law were passengers on board MH370 when it disappeared, told Sun-Herald of her anger at the book's release.
"Nobody knows what happened so why would anyone want to put out a book at this stage?" she said.
"There's absolutely no answers. It's devastating for the families. It's 10 weeks tomorrow and there's nothing."
The release of Cawthorne's book came as Rupesh Paul promoted a film to be made about the missing plane, entitled The Vanishing Act, at the Cannes Film Festival.
Though associate director Sritama Dutta said the film had "no similarities" to MH370 because the "true facts keep changing every day", a trailer posted to YouTube on Saturday and promotional posters suggest it reveals "the untold story" of the Malaysia Airlines flight.
Paul told Variety he plans to release the film worldwide in September. In March, an Australian film called Deep Water was shelved because it contained "uncomfortable similarities" to the disappearance of MH370.
