Authorities have identified the woman found dead Tuesday in a residence on Avenue B in Billings.
Shanna Lynn Booth, 32, died of undetermined causes with no obvious signs of why she died, Yellowstone County Coroner Rich Hoffman said Friday.
Billings police have called the death suspicious and related to a crime spree that left another woman dead in the same area and two others dead in a murder-suicide in Gallatin County.
The incident began when police were called for a welfare check and found a 64-year-old woman, later identified as Roxann Renee Watson, dead inside from an obvious homicide.
Later that night, authorities issued an attempt to locate order for two suspects, 28-year-old Erika Miller and 22-year-old Henry Porter, who were later found dead in an apparent murder-suicide in Gallatin County.
Miller was Watson's daughter, and Porter was Miller's boyfriend.