Mother: My son is missing.
911: How old is your son?
Mother: He's like 4 days old.
911: He's what?
Mother: He's 4 days old.
The baby's mother told dispatchers her half-sister Kristen Smith was in her home the night before.
But when she woke, her infant son and Smith were both gone.
The newborn was later found behind a gas station in Iowa.
The FBI says Smith has admitted taking the baby. She is being held without bond.
