In the 2290s decade, Doctor Dax was part of the science team working in a duck blind on Eta Eridani II, a planet inhabited by intelligent but savagely brutal, telepathic natives. The mission was led by Doctor Amanda Grayson of Earth, and the security detail was provided by the Interstellar Guard. The Interstellar Guard hoped the Eridanians could be gained as allies or weapons in a coming war with the Klingon Empire.
The S'chn T'gai clan of ShiKahr used their mental prowess to overrun the duck blind and capture its personnel in the year 2293. Except for the scientists and Trooper Demora Sulu, all Interstellar Guard personnel was killed and their corpses suspended from the ceiling.
When the iUES Kumari II arrived to investigate, Commander Hikaru Sulu made contact with T'Pau, clan leader. To prove their resolve, T'Pau had Doctor Dax decapitated. A messenger delivered Tornellen's head to Commander Sulu.