Eva Thorne, real name Mary Perkins, was a corporate "Fixer" at one time employed by the DoD for Global Dynamics to increase their profits. During the events of From Fear to Eternity she was revealed to have been a Eureka founder, and over one-hundred years old. She was the sister of lead scientist Jimmy Perkins in developing the atomic bomb, but, during the first ever test, created a byproduct dubbed "Element X". When Jack Carter questioned this saying the first tests were in Los Alamos, she replied, "They learned from our mistakes and went with plutonium". Element X caused the scientists to age and die in a month, while the speed of Thorne's aging slowed exponentially. Her current location (and identity) is unknown, having escaped custody of the DOD and fled Eureka with the help of Henry Deacon and Jack Carter. This led to Mansfield firing Carter, though he was returned his job in the episode "Welcome Back, Carter".
What happened to her, or if her fate was changed, wasn't brought up in the new timeline.