Professor Laura Mulholland was a scientist.
"I was arrogant and blinkered enough to open Pandora's box. I cannot live with the demons I have released."
After meeting the Doctor, though, the cause of her death changed. The Selachians were going to take the last G-bomb, which was on the Triumph, and use it to destroy Earth. Unable to defuse it in time, she climbed on top of it with a grenade. She was gunned down by the Selachians, but not before activating the grenade. Four seconds later, the explosion cause the G-bomb to detonate, destroying the ship and all the Selachians on it. (PROSE: The Final Sanction)