Police was called to the Salvation Army store after an employee found some blood on the bathroom floor and then the body, which was inside a plastic bag with its umbilical chord still attached.
The placenta was also discovered at the scene.
The baby boy was pronounced dead on the scene, according to a release from Streamwood police.
Salvation Army store officials told police the woman appeared pregnant when she walked into the store on Friday morning and asked a manager to use an employee restroom.
The woman walked out an hour later, they said.
James Keegan, Streamwood Deputy Chief told NBC Chicago: “She looked distressed [and] disheveled.
“The manager sent a worker to into the store to check on the status of the bathroom, discovered some blood on the floor and then subsequent to that we discovered – the worker discovered – a fetus in the wastepaper basket.
“It wasn’t premature or born with a light weight. It looked like it went through a nine-month gestation.
“The baby was delivered alive and strangled to its death.”
She was last seen wearing a purple hooded sweatshirt and a lime green coat and may have been with another woman and a two-year-old child.
Deputy Chief James Keegan offered the reminder of Illinois’ Safe Haven law, which allows mothers to leave babies 30 days old or younger – no questions asked – at any police station, fire house or hospital.
Anyone with information can contact the Streamwood police investigations division at (630) 736-3700.
A confidential tip line also is available to anonymous callers at (630) 736-3719.
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