Sasha lived with Tanya, Irina, and Kate as a member of the Denali coven, and it is often assumed that she was the creator and mother of the three members of the coven who existed at the time (Breaking Dawn, pg. 33). The Volturi executed her upon her creation of Vasilii, an immortal child. Her daughters did not know of Vasilii's existence, so they were not killed, but they were forced to witness her death (Breaking Dawn, pg. 35).
'Just checking.' He [Edward] ran his hand through his tousled bronze hair. 'You might have changed your mind. Most people seem to enjoy things like birthdays and gifts.' - New Moon, Page 9
