The baby was found in good condition late Tuesday — four days after being abducted — and the woman accused of the crime, Shannon Torrez, was arrested.
In court papers, authorities said Torrez, 36, learned about the week-old baby through a "welcome home" yard sign for the new mother, Stephenie Ochsenbine.
Sheriff Gary Toelke said Torrez told investigators she was nine months pregnant but lost the baby on Friday, the same day little Abigale Lynn Woods was kidnapped. But Toelke said investigators are trying to determine whether Torrez had been pregnant.
"There is speculation maybe she wasn't," Toelke said at a late afternoon news conference. There also was no sign of a stillborn baby, he said.
Investigators questioned how Torrez could have delivered her own baby and recovered enough physically to attack Ochsenbine on the same day.
Torrez was arrested Tuesday after her sister-in-law, Dorothy Torrez, contacted authorities.
"She's the hero," the sheriff said.
when she noticed makeup on the forehead of the baby her sister-in-law claimed was her own, authorities said. She rubbed off the makeup and found a strawberry-red birthmark that matched the description of the kidnapped infant, investigators said.
She contacted police, and hours later the healthy 11-day-old baby was reunited with her parents and Shannon Torrez was taken into custody.
On Wednesday, Ochsenbine cradled her daughter and said the experience had been exhausting.
"It's just unbelievable," mother Stephenie Ochsenbine said on CBS News' The Early Show, hours after her 11-day-old infant, Abigale, was reunited with her parents.
"I'm great now, definitely great now," Ochsenbine said.
Ochsenbine told police that a woman entered the rural home, attacked her with a knife and stole Abby. During the search for Abby, investigators theorized that the abductor who had recently lost a child or was unable to have children.
Shannon Torrez lives a few miles from Ochsenbine's home. She was being held on $1 million bond and was to be arraigned Thursday.