Who betrayed Sarah Aaronsohn?

Hillel Halkin's next book sounds extremely interesting. He's revisiting Nili, the Jewish spy network based in Zichron Ya'akov which worked for the British against the Ottomans during the First World War, and is shedding some new light:

[A]s I began reading about it back in the mid-1970s, I came across two mysteries that were to form the main thread of my book. The first was an account that I found of what happened when the Nili spies were arrested by the Turks in 1917. Several of the spies came from the village, and those arrested in it were brutally interrogated by the Turks on the spot. In this account it was related that one of the apprehended spies was taunted and assaulted by four local Jewish women who fell on him like Furies and cheered the Turkish soldiers as he was being marched through the streets of the town. The eerie nature of this scene fascinated me. Yet it also puzzled me because I knew that the Jews of Palestine during World War I were not pro-Turkish; on the contrary, they thought of the British army, then at the southern gates of Palestine, as their salvation from a corrupt and despotic regime that was bleeding the country for its war effort. I wanted to find out why these women acted as they did.
The second mystery had to do with one of the four — who, in this same account, was said to have died a "strange death" not long after these events took place. What was so strange about it? The more I asked the old-timers in town who remembered her — she died in 1921 — the less strange it seemed to have been, until one day Epstein's curious reaction to a question of mine led me to suspect that she had been murdered as an act of revenge for informing on the Nili to the Turks and that he alone knew of it. My attempt to find out the truth about this forms the main "plot" of the book, though it's one on which other material is hung.

Sounds intriguing, although I always thought the spies were caught when one of the ring's carrier pigeons was intercepted by the Turks and another member of the gang, Belkind, was captured and gave the game away. Perhaps he didn't after all?
Of-course, no matter how original, provoking and sophisticated Halkin's book is, for an entire generation of Israeli kids, the only book which will ever really count on the subject is Sarah Giborat Nili ('Sarah the Heroine of Nili), Dvorah Omer's heart-breaking account of the affair for children. I first learned Hebrew by reading an abridged version in easy language, and still remember getting upset over Avshalom Feinberg's death. I hope Halkin knows he's treading on hallowed ground!