Authorities said that an 18-year-old Chicago woman has been charged with the murder of her newborn son.

According to the Chicago Tribune, Ana Rosa Mora is facing charges of first-degree murder for allegedly placing the infant in a plastic bag and leaving him outside to die.

Mora allegedly gave birth to the baby last Saturday morning and on Monday, showed staffers at her high school a picture of child she claimed was hers. School employees became suspicious of her, however, after she lied about the baby’s age and called the police.

Assistant State Attorney Glen Runk said that the teen later admitted that she downloaded the image of the infant she showed them from the internet.

NBC 5 noted that the deceased child was around 8:30 a.m. the same morning Mora had given birth. Investigators said that the umbilical cord and placenta were still attached.

The medical examiner’s office concluded that the child died of asphyxia and possible exposure.

Mora was arrested and is being held on $500,000 bail.