Authorities say a box containing bones and teeth that are believed to be from three children was found in the shed of a Missoula home in September.
The Missoulian reports that Missoula police launched an investigation after a cleaning crew found the box when the former tenant was evicted from the property. Police confirmed that information to CBS affiliate KPAX.
Police documents say the Montana State Crime Lab verified the remains as human, and an anthropology professor at the University of Montana determined they were "likely modern and not archaeological."
The professor estimated the ages of the children to be 2-4 years old, 5-8 years old and 6-10 years old.
Police obtained a search warrant for a potential homicide in late November, but no additional evidence was gathered.
A Missoula police spokesman told the paper that the investigation remains active. No suspects have been named, KPAX reports.