The girl was just a day old when her 23-year-old mother walked into the emergency room at Inova Fairfax Hospital last year, holding the tiny body, according to a search warrant.

The woman later told police that the baby had died during birth, the search warrant shows.

Then she told them she dropped the baby soon after the birth, resulting in the girl’s death. A third explanation would follow.

But Fairfax County authorities revealed Thursday what they think is the truth: Adriana Teran killed the newborn.

Teran was indicted on charges of first-degree murder and child abuse. A conviction could mean a life sentence.

Fairfax police declined to discuss why Teran, a Fairfax area resident, would allegedly take her child’s life.

The search warrant indicates that Teran arrived at the hospital with the girl’s body on May 8, 2013.

A doctor examined Teran and the newborn, the search warrant shows. She told them the baby had been born the day before.

Fairfax police said Thursday that the baby was born at Teran’s home in the 4700 block of Old Forge Court.

The doctor who examined the newborn discovered that she had a skull injury, according to the search warrant.

“Doctors determined the infant had died of ‘trauma,’ ” said Lucy Caldwell, a police spokeswoman. “They felt the circumstances surrounding the death may have been ‘suspicious.’ ”

The doctor alerted a police officer in the emergency room and told him what she had found.

The newborn’s body was taken to the medical examiner, who performed an autopsy.

Police said the examiner determined that the baby had died of blunt-force trauma to the head. The death was ruled a homicide.

Detectives did three interviews with Teran, and each time she gave a different explanation about what happened to the baby, according to the search warrant.

The third explanation was that Teran had dropped the infant twice and she died.

The public defender’s office, which is representing Teran, declined to comment. A call to a number listed for her and family members went unreturned.

A hearing in the case is scheduled for July 3.

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