Before this, she was apparently the sub-overseer for Facility Eight, one of the many facilities owned by the Eden Organization.
In a yet to be explained incident, she let Agents of The Slender Man into the facility; whereby they then began to destroy it with the aid of Slender Man. During her dying moments, she was apparently connected to one of the "Memory Imprint" devices owned by the Organization. The Manufactured Newborn used this connection to turn her into a Thoughtborn, stripping her mind from her conscious.
Interestingly, this is implied to have happened on the 5th November, 2010- which is before The Manufactured Newborn's creation. This could imply the theory about it being a trans-temporal being is correct.
Another possible theory is that her mind remained in stasis whilst connected to this network; slowly degrading until it was found by The Manufactured Newborn. If true, this could possibly explain why her comments are written in a strangely chaotic style.
However, this story has only been mentioned by The Overseer, so it is unknown if this is the truth. What has been implied is that she is the mother of Aura, and that she chose the name Morganna Le Fay in reference to the Morganna of .hack, adding to the reference Aura herself made.