Police say Torrez, 36, abducted 7-day-old Abigale Lynn Woods on Friday after slashing the throat of the infant's mother, then tried to pass the newborn off as hers for five days before being turned in to authorities on Tuesday by her sister-in-law.
Franklin County Prosecutor Robert Parks said Torrez could face life in prison if convicted.
Police say Torrez told them that after giving birth to a stillborn child Friday morning, she drove by Stephenie Ochsenbine's home a few miles away on Missouri 47 and saw the "Welcome Home Abby" sign that stood in the yard.
Investigators wonder how a woman could deliver a baby, deal with its apparent death, and then recover enough to mastermind a kidnapping all on the same day, reports CBS News correspondent Lee Cowan A search of her home has turned up no sign of a stillborn or a miscarriage.
Franklin County Sheriff Gary Toelke said investigators continue seeking hard evidence that would support Torrez's tale.
Torrez had told neighbors and family she got married last New Year's Eve and was expecting a baby, reports John Mills of CBS affiliate KMOV St. Louis. Neighbors say she appeared to gain weight, but police say they are trying to determine if she was ever pregnant.
There's a solid profile of women who steal other women's babies, say experts.
"These are women of child-bearing age, they tend to be married or at least living with someone, they all claim that they have miscarried or had a stillbirth or can't have children and they tend to abduct close to home in their communities or near by," Ernie Allen of the National Center of Abducted and Exploited Children said on CBS News' The Early Show.
"In the vast majority of the cases we have seen, they have not" miscarried, Allen added.
Torrez reportedly stopped at the home, asked to use the phone, then attacked Ochsenbine, 21, with a knife and left with the baby.
A frantic five-day search ensued, drawing international attention to the rural area 45 miles southwest of St. Louis. But on Tuesday afternoon, the baby was returned and Torrez arrested Tuesday after the suspect's sister-in-law, Dorothy Torrez, contacted authorities.
Shannon Torrez, who also went by Shannon Beck, told her sister-in-law on Sunday that she had given birth on Friday, FBI agent Roland Corvington said. Visiting Shannon Torrez the next day, Dorothy Torrez persuaded her sister-in-law to take the baby to see a doctor, and on Tuesday the two women went to St. Louis for that doctor's visit.
Dorothy Torrez became suspicious that day when she noticed makeup on the forehead of the baby. Using the baby's cap, she rubbed off the makeup and found a strawberry-red birthmark that matched the description provided by investigators who were seeking an abducted baby.
After confronting her sister-in-law, Dorothy Torrez contacted police, and hours later a healthy 11-day-old Abigale Lynn Woods was reunited with her parents. Shannon Torrez was taken into custody.
Shannon Torrez lives just a few miles from Ochsenbine's home near Lonedell, Corvington said. She worked as a nail technician for a year-and-a half in St. Charles before being fired in 2005 for unprofessional behavior and not having a license, according to Vel Green, director of Spa Winghaven.
Abby's family members fanned out Wednesday and tore down missing baby posters at service stations, on street signs and at other public places.
Ochsenbine's grandfather, James Ochsenbine, said the weekend was emotional torture for the young couple and relatives.
"They went through quite a lot," he said. "I couldn't really say there's a silver lining to it, except for the idea that Abby is back safe and sound and as beautiful as ever. And she's going to be safe from now on."