While returning to Federation space in 2371, Captain Cusak sent the ship to investigate an exogenic energy field surrounding the fourth planet of a star system in the Rutharian sector. When the Olympia scanned the energy barrier, it triggered a quantum reaction that sent a surge of metreon radiation that disabled the Olympia's engines, causing it to crash on the planet surface. Captain Cusak was the only survivor.
The planet's energy field caused her distress signal to be transmitted three years into the future, where it was picked up by the USS Defiant. The Defiant attempted a rescue, not knowing that Cusak had already been dead for three years. (DS9: "The Sound of Her Voice")