The baby boy was four days old when he died just before 2 p.m., according to the Cook County Medical Examiner's Office.
Chicago police said he was the son of Stacey Jones, a 35-year-old Cook County probation officer who was found unresponsive on the porch of her home in the 2100-block of East 95th Place just after midnight Tuesday.
Jones, a mother of two, was eight months pregnant. Police said she was found with two gunshot wounds.
Jones was rushed to the University of Chicago hospital in critical condition, where she later died, police said.
Doctors were able to deliver her baby, who remained in critical condition until his death Saturday at University of Chicago Medical Center.
Chicago police said Thursday a suspect in Jones' death was released without charges.
Police said they are focusing their investigation on people who were known to the mother of three.
Timothy Evans, chief judge of the Cook County Circuit Clerk, confirmed Jones had worked as a probation officer in the court's Adult Probation Department since April 2019.
"Our thoughts go out to her family, colleagues and friends at this difficult time," Evans said in a statement.
A GoFundMe page set up by her labor union to help with medical expenses for her newborn baby said, "Stacey was a Cook County Adult Probation officer who worked with offenders providing resources, monitoring and guidance in an effort to assist them in changing their lives."
Neighbors said Jones, who is originally from Tennessee, had lived at the address of the shooting for less than a year. They last saw Jones playing outside with her other two young children last Saturday.
"I just saw her Friday, and she was telling me how happy she was that she was about to have a baby," said Nicholas Minor, a friend and coworker. "Stacey was a very perky person, you know, always had a smile every morning coming to work. Every day, every time I saw her she'd say, 'Hi Nick!'"
Minor said her job was her passion, but Jones' pride was her children. He said her murder not only stole her future, but robbed her boys of a loving mother.
Pregnant woman fatally shot in Jeffery Manor on South Side; baby in critical condition, police say
Area Two detectives are investigating the shooting.
They said police found racially-tinged graffiti on the side of Jones' apartment, but believe it was placed there as a diversion.
Anyone with information is asked to call CPD or text 274637 to submit a tip anonymously.