NASHVILLE, Tenn. -- A 4-day-old boy taken from his mother after she was stabbed at their home has been found in good health in Alabama, Metro police said late Friday night.

Related: Criminal Complaint Against Tammy Renee Silas (PDF) | Images

Tammy Renee Silas, 39, was formally charged Saturday with federal kidnapping. She will be transferred to Nashville, where proceedings will take place.

The boy was recovered Friday from an Ardmore, Ala., home.

Police said the break in the case came from information developed from a photo of a Kia Spectra in a Wal-Mart parking lot. The car was seen following Yair and his mother, Maria Gurrolla, as they left the Nolensville Road store Tuesday.

Investigators determined that Silas had rented the vehicle Tuesday from Nashville International Airport.

The Tennessee Bureau of Investigation released a sketch Friday of a person of interest, whom Gurrolla had described as a heavyset white woman who spoke some Spanish.

Gurrolla told police that a woman posing as an immigration agent said she wanted to see the woman's papers before stabbing her about eight times with a knife taken from her kitchen.

According to the criminal complaint against Silas, Gurrolla heard her say on the phone something to the effect of "The job is done" in Spanish.

Gurrolla visited Saturday afternoon with Yair; however, the Department of Children's Services has taken the four children in her household into foster care until further notice. Arrangements will be made with Gurrolla for visitation.