A Crystal couple will not be charged in the death of a newborn baby found buried in their back yard earlier this year, authorities said Friday.

According to the Hennepin County attorney's office, there were conflicting stories of whether the baby girl, who was estimated to be at 30 to 38 weeks' gestation, was born alive. Because of the number of years that the baby's remains had been buried, the Hennepin County medical examiner's office said it was impossible to determine if she was born dead or alive or if any injury was inflicted.

"In order to charge someone with a crime, we need sufficient admissible evidence in order to prove our case beyond a reasonable doubt to a jury or judge," Hennepin County Attorney Mike Freeman said. "Despite an excellent investigation by Crystal police and other agencies, that evidence does not exist."

In late February, after they responded to a domestic call at a home in the 5700 block of Quail Avenue N., where a 30-year-old man and a 28-year-old woman lived, authorities received information about the infant's remains when the man walked into the Crystal Police Department and told officers he had buried a dead baby in the back yard about four years ago.

Police arrested the couple and spent a day thawing the ground and then digging up the remains of the baby.

The couple was charged on an unrelated domestic assault case, but both were released from jail without charges in connection with the infant's death.

Unless substantial new evidence is developed, the case is considered closed, authorities said.

Nicole Norfleet • 612-673-4495 Twitter: @stribnorfleet