"We have to strive for what it is we want," she wrote.
Then she outlined a chapter on the "reasons for fighting and leaving all you love behind."
"The situation is such that many times your own families — mothers, fathers — cannot even know that you are a mujahid etc... What does it mean for you to be a stranger?"
These words may offer the only clues to her state of mind in Aylesbury when she is believed to have shielded her radical views from friends and family alike. And they may explain why people in Aylesbury had no inkling there were extremists in their midst.
On Sept. 21, al-Shabab terrorists attacked the upscale Westgate Mall in Nairobi with grenades and assault weapons, killing at least 67 people. Early eyewitness reports that a white woman took part in the raid led to fevered speculation that Lewthwaite was involved.
"White widow exclusive: Mother of all terrorists!" read a front-page headline in London's Daily Mirror tabloid.
Some British tabloids persistently referred to her as the mastermind of the slaughter — without a scintilla of evidence that she was even in Kenya.
At roughly the same time, her second husband was reported to have been killed in a shootout in Somalia between rival al-Shabab factions, making her a widow once again.
Lewthwaite became the subject of an international search on Sept. 26 when Interpol called for her arrest among its 190 member nations. But the "red notice" linked her to the failed 2011 Christmas plot, not to the Westgate Mall killings.
It says she is wanted for "being in possession of explosives" and "conspiracy to commit a felony," though the timing of the Interpol notice — issued just five days after the mall attack — led many to assume that police believe she had a role in that as well.