Investigators said Tuesday they have solved the decades-old mystery of who were the parents of a newborn girl whose remains were found in a ditch south of St. Cloud, but lack the evidence to charge anyone in connection with the death of the child.

Two women on their usual walk along a road on April 3, 1980, spotted the baby wearing only a disposable diaper and alerted the Stearns County Sheriff's Office. The discovery set off the long-running investigation that included multiple autopsies, an exhumation and numerous search warrants executed within and beyond Minnesota in order to collect DNA from anyone who might be related to the child, known throughout the years as Jane Doe.

Sheriff's Lt. Zach Sorenson told the Star Tribune his office has determined the identities of the parents. Sorenson said the mother has died, while the father is living in Minnesota and has spoken with a Sheriff's Office investigator.

Sorenson said once the case is considered closed in the coming weeks, their names and other details of the investigation will be released.

In the meantime, Jane Doe is back in her initial resting place in St. Cloud at Calvary Cemetery — Block 11, Row 5, Grave 1A — after her exhumation in 2018.

And just as it was upon her initial burial a few days after being found, Jane Doe's plot still lacks a marker.

While one mystery has been put to rest, the Sheriff's Office acknowledges it can't solve another: whether the baby was alive when left by the side of the road near the St. Boniface Chapel in St. Augusta.

And lacking that determination, Sorenson said, there is no way his office can send the case to prosecutors for consideration of charges.

"We haven't been able to prove beyond a reasonable doubt that there is a criminal element to the child's death," he said. "We couldn't prove the baby was alive or dead when left there."

Sorenson declined to specify the one or multiple breakthroughs that led to learning the names of Jane Doe's parents, but the decades of investigative work put into the effort were outlined in a search warrant affidavit filed last week in St. Louis County District Court that allowed law enforcement to collect DNA from one prospective relative.

According to that court filing from April 2022 that was unsealed only last week:

The full-term newborn's remains were sent to Hennepin County for an autopsy, which determined that she was white, wearing a soiled diaper, and showed no obvious cause of death. She was buried four days later as Jane Doe.

Law enforcement searched the area for leads that might reveal the names of the parents and checked a government list of all females born in the county going back to November 1979. No luck.

A court order in August 2018 allowed for Jane Doe to be exhumed by Ramsey County Medical Examiner Michael McGee.

McGee "opened the cherub and removed several bones from the deceased infant's body for the purpose of developing a DNA profile," read the affidavit signed by Stearns County Sheriff's Office investigator Tony Kotschevar. However, the state Bureau of Criminal Apprehension (BCA) told investigators there was not enough DNA in the samples to build a profile.

Investigators went back to the Hennepin County Medical Examiner's Office and learned it retained small pieces of Jane Doe's organs during its autopsy, soaked them in formaldehyde and sealed them in paraffin wax.

These samples allowed the BCA to develop a profile in 2020 that could be used to check various DNA data bases for a match. A lab in suburban Washington, D.C., issued a report in May 2021 that the DNA indicated that Jane Doe's family would have traits that include fair to very fair skin tone and green or hazel eyes.