SPARTANBURG, S.C. -- Spartanburg County deputies said that a mother admitted to placing a pillow over her newborn's face on Monday.

Deputies said that 20-year-old Jessica Smith and her friend showed up at the Chesnee Family Medical Center on Monday afternoon with her 3-month-old baby, who was deprived of oxygen and severely dehydrated. They said that the baby was admitted into the pediatric intensive care unit.

Investigators said that the following day the infant began having seizures that did not respond to seizure medication. They said that an MRI revealed that the baby had suffered an injury to his brain, which indicates he was suffocated.

Deputies said that Smith told the hospital staff that she left the newborn in a bed to sleep for a period of time and when she returned to check on him several hours later, there was a pillow on the baby's face. She told the staff that the boy's lips were blue when she removed the pillow.

Investigators said that while Smith was being prepped for a polygraph she admitted to investigators that she had placed the pillow over the baby's face.

Smith was charged with child neglect and child abuse.