Investigators in New Hampshire are promising that new information will soon be available in one of the nation’s strangest so-called Jane Doe cases. Hunters first found the remains of a woman and a girl stuffed in a barrel in Allenstown, New Hampshire, 30 years ago. It took another 15 years for authorities to discover that there was another barrel just 100 yards away containing the remains of two more young girls.

None of the four have ever been identified.

Now the New Hampshire State Police is working with the National Center for Missing and Exploited Children and the FBI to use new technology called isotope analysis that at least may help determine the region in which the victims lived. Authorities determined at the time that at least two of the victims were beaten to death, but it’s never been clear whether the four were biologically related to one another.

According to a Boston Globe story this week, investigators have scoured missing-persons reports, reviewed school records for children reported absent and interviewed nearby residents, but the trail has gone cold. A retired state police sergeant named John Cody who once worked the case said he did not blame police for taking so long to find the second barrel “because it was a football field away from where the first one was found and wouldn’t have been considered part of the initial crime scene,” according to the Globe.

But CNN described the circumstances of the investigation differently in a 2013 story about the Jane Does. According to the network, even though New Hampshire has an exceptionally low number of annual homicides, a man was coincidentally murdered in Hookset, New Hampshire, in an unrelated incident shortly after the first barrel was discovered, “and that murder became the priority of the police force,” i.e. state troopers. That killing was eventually solved 10 years ago.

According to CNN, “policy called for troopers to look into a cold case if they were not working on a current homicide,” so a trip from an investigator to the scene of the first barrel finally led to the second being discovered in 2000. A sergeant acknowledged to CNN “that many may question why it took 15 years to find a second barrel 100 yards from the other.” However, reported CNN, the sergeant “cited resources needed for the Hookset murder, the number of people in the major crime unit and the fact that autumn leaves covered much of the property.”