Katie Russell was Owen Harper's fiancée before he joined Torchwood 3. She was believed to suffer from Alzheimer's disease, which would make her the youngest case ever. Owen did not trust this and ordered examination after examination, even though none showed up anything unusual. Eventually after a last brain scan the doctors thought that she had a brain tumor. During the operation it turned out that she was infected by an alien creature, which in self defence killed both the doctors and Katie herself, to the devastation of Dr. Harper.
She was working as a junior doctor at the same hospital as Owen. (TW Fragments)
