The information in this article comes from Marvels, warlord of mars and is not written by Edgar Rice Burroughs.
Saar was a Kaldane, and the love of "her" fellow Kaldane Aard. When Aard was banished for his emotions the king Taak remade Saar, implanting her brain in the body of the red martian woman Vala Dia so that Saar could be a spy amongst the red peoples, she was also told that her lover Aard was dead.
The implantation process seemed to physically mutate the head of the body into a Kaldane, making the process irreversible, at least for Vala Dia. John Carter slew her and the other human-seeming Kaldanes.
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