Sgt. Jennifer Pound says 51-year-old April Peregooda was unresponsive when Mounties attended the Alouette Correctional Centre for Women last Friday.
Peregooda, who was from Vernon in the province's Southern Interior, was later pronounced dead at the hospital.
Pound says Mounties suspect foul play and have arrested a woman in connection to Peregooda's death, but the woman has not been charged.
Investigators are now speaking to other inmates, and an autopsy is expected to be performed to confirm the cause of death.