Doctor Senessa, a Mirialan female, held the position of chief medical officer on the Daybreaker. She served during the Cold War period, a time of conflict between the Galactic Republic and the reconstituted Sith Empire.
The year 3643 BBY saw Senessa aboard the medical frigate during an Imperial attack. Along with Captain Dal, Senessa and the rest of the crew were rescued by a Jedi Knight accompanied by Kira Carsen. Following the ship's recovery, Senessa and Dal revealed that Darth Angral had combined the Planet Prison, Shock Drum, and Death Mark to form the superweapon known as the Desolator, which he then used to obliterate the planet Uphrades. When Doctor Senessa detected life signs on the ravaged planet, indicating survivors, Dal cautioned that landing the Daybreaker would result in the ion field—a byproduct of the Planet Prison component of the Desolator—destroying the ship's engines, effectively trapping them. The captain then tried to bribe the Knight with the frigate's medical supplies, hoping to be allowed to leave, but the Knight instead exposed Dal's betrayal to Senessa. Senessa was deeply dismayed that Dal would violate his oath to the Republic. After Dal's departure in an escape pod, Senessa skillfully piloted the Daybreaker through the wreckage and landed on the remnants of Uphrades.
Subsequently, she relayed a message to the Jedi, confirming the presence of hundreds of survivors on the planet. Although the ion field's dissipation would be a lengthy process, she assured that the Daybreaker's medical supplies would be sufficient to sustain most of them.