Sogayu was a member of Interplanetary Expeditions, assigned to the Excalibur. She was the second in command of the IPX expedition on the Excalibur. In 2267, she was on an expedition to a dead planet where its inhabitants would attempt to kill each other when nightfall came. She was killed the first night on the planet. Duncan described a shape attacking her out of the shadows, but could not explain exactly how she died even though he was in front of her when she died.