A week ago, Maria Gurrolla was celebrating the birth of her fourth child. A blue yard sign announced: "IT'S A BOY!" She visited a local welfare office that helps low-income mothers.

Then an attacker posing as an immigration worker arrived at her home south of Nashville, stabbed the 30-year-old mother and snatched away her 4-day-old son. The newborn was found safe, but after a brief reunion, state officials took the baby away from Gurrolla again, along with her other three children.

Now Gurrolla is left to wonder when she might see any of them again. A judge will review the case this week to determine when Yair Anthony Carillo and his siblings — ages 3, 9, 11 — can come home.

State officials say the children were taken into custody Saturday for safety reasons but have not offered details. A spokesman said a hearing must occur within three days of when the children were taken into state custody.

Tammy Renee Silas, 39, was arrested and charged with kidnapping. She waived her initial court appearance in Alabama on Saturday and is expected to be brought to Tennessee sometime this week, FBI spokesman Joel Siskovic said Sunday. She was appointed an attorney, but Siskovic didn't know the lawyer's name and the jail wouldn't release any information.

Police have not released a motive, but Silas' live-in boyfriend said she told him she could not have children and wanted to adopt a child from a relative who was going to jail.

Gurrolla had returned home with the infant and her 3-year-old daughter on Tuesday when she answered a knock at the door.

A heavy-set woman with blonde hair claimed she was an immigration agent and wanted to know about false information Gurrolla had given during a visit that morning to a Women, Infants and Children, or WIC, office. WIC is a federal program that provides vouchers to women to purchase approved foods at grocery stores and pharmacies.

Gurrolla's attacker stabbed her with a knife eight times, mostly in the neck and chest. When the woman briefly walked away, Gurrolla darted to a neighbor's house, pleading for help. Sometime after that, the kidnapper fled with the newborn.

Gurrolla was left bloodied from head to toe, a long scratch on her face. When she held a news conference Tuesday from the hospital to plead for her baby to be found, her eyes were bloodshot and her face was swollen.

Gurrolla has told police that she heard the attacker talking on the phone in Spanish, saying, "The job is done" and that the mother "was dying."

Authorities have not said whether they think anyone else was involved.

Police found a surveillance tape from a local Walmart showing a Kia Spectra with Indiana tags that appeared to have followed Gurrolla. It turned out to be a rental from the Nashville airport, and a phone number registered with the rental led police to Silas on Friday night.

Investigators were talking with her live-in boyfriend, Martin Rodriguez, when Silas appeared holding the infant, covered in a blanket.

Speaking through an interpreter, Rodriguez told The Associated Press that Silas told him she was adopting a baby from a cousin who had to go to jail, and was going to El Paso, Texas, to get the child.

He said Silas had a newborn with her when he picked her up from the Huntsville airport Tuesday. The rental car was returned in Huntsville, authorities said.

"She was acting normal around the baby, and I didn't really see any difference, but I think she was happy," Rodriguez said from their one-story home, where a box of baby clothes for a boy overflowed in the dining room. "What woman isn't happy to carry a baby?"

Rodriguez said the last thing she told him was: "I am so sorry, and I love you."

Siskovic, an FBI special agent in the Memphis division, said there was no indication of an ongoing threat to Gurrolla's family. He could not say why the children were in state custody.

Gurrolla was briefly reunited with her son on Saturday, and authorities said she was allowed to hold him. State officials then took custody of all the children.