Marlen Ochoa-Lopez, 19, was 9 months pregnant when she was killed, and the baby was removed from her body and taken to Advocate Christ Medical Center, where he later died. An attorney said the family has received bills for her son's treatment from the hospital.
Clarisa Figueroa and her daughter Desiree were already facing first degree murder charges for allegedly killing 19-year-old Marlen Ochoa-Lopez. They remain in jail after prosecutors charged the duo with the murder of her son Thursday.
RAW VIDEO: Missing pregnant teen's remains found near Chicago home
RAW VIDEO: Chopper7HD over home where missing pregnant teen's remains found
"The medical examiner determined that the cause of death was anoxic encephalopathy, which is when the brain tissue is deprived of oxygen; intrauterine hypoxia, which is when the fetus is deprived of an adequate supply of oxygen; and maternal assault," Cook County assistant state's attorney James Murphy said.
WATCH: Attorney for the family of murdered mother addresses media following baby's death
Attorney representing the family of Marlen Ochoa-Lopez holds news conference on baby's death
"The presumption of guilt is not evident and the evidence does not show that my client is guilty," the public defender for Clarisa Figueroa told the court.
Judge Mary Marubio denied both women bond. They were originally charged with only aggravated battery to a child for removing the baby from his mother's womb after they allegedly strangled her to death. The Figueroas, along with Clarisa's boyfriend, who is charged with concealing the homicide, have all pleaded not guilty.
In a statement, Ochoa-Lopez's husband said: "We are grateful that charges have been placed on these murderers. There will never be a day that we are not grieving for my wife Marlen & my son Yovanny."
Prosecutors said after the women took the baby from the dead woman's womb, the child was taken to Advocate Christ Medical Center where he eventually died.
Clarisa Figueroa was allegedly able to pass off the baby as her own for weeks. While an investigation by the state cleared the hospital in the case, an attorney for the Ochoa-Lopez family said invoices sent to the family prove their negligence.
Frank Avila, the lawyer for the father of the baby boy, confirmed to ABC News that he has received over $300,000 in hospital bills for the care of his newborn.
"We don't have the medical records and my client is getting bills of hundreds of thousands of dollars from the hospital that has the Figueroa name on it and that is atrocious," Avila said.
The family's attorney said he plans on filing a lawsuit against the hospital.
The hospital released a statement Thursday evening, saying, "Our hearts and prayers continue to be with the Ochoa-Lopez family during this difficult time. We have had discussions with the family regarding a bill that was inadvertently sent and we regret this error. We take our obligation to patient privacy seriously, and therefore are unable to comment further regarding care, services or billing."
WATCH: Artist adds baby Yovany to memorial mural for Marlen Ochoa-Lopez
Artist adds baby Yovanny to Pilsen mural
PREVIOUS COVERAGE
Artist unites murdered pregnant teen mom and baby on Pilsen memorial mural
Marlen Ochoa-Lopez's family outraged after state clears hospital in her baby's case
Christ Medical Center acted properly in Marlen Ochoa-Lopez baby case, investigation finds
Marlen Ochoa-Lopez death: Baby of murdered pregnant Chicago woman dies, family spokesperson says
Marlen Ochoa-Lopez death: 3 suspects in murder of pregnant Chicago woman formally indicted
Marlen Ochoa-Lopez baby: Family gets 2nd opinion on infant's prognosis
Family, community says final goodbye to Marlen Ochoa-Lopez
Marlen Ochoa-Lopez's visitation continues Friday; Murdered woman's baby remains hospitalized
Marlen Ochoa-Lopez Death: Murdered Pilsen woman's family arrives in Chicago, visits baby in hospital
Marlen Ochoa-Lopez Death:'We can still find hope': Artist creates mural of murdered Pilsen woman
Marlen Ochoa-Lopez Death: Murdered Pilsen woman's family arrives for funeral, health department investigating Christ Medical Center
Marlen Ochoa-Lopez's family seeks answers why authorities were not alerted to Figueroa
DCFS, police not alerted to Marlen Ochoa-Lopez death suspect despite no signs of giving birth, officials say
Funeral set for murdered pregnant woman Marlen Ochoa-Lopez
Marlen Ochoa-Lopez death: 3 charged in murder of pregnant Chicago woman denied bond
Marlen Ochoa-Lopez death: 3 charged in murder of Chicago missing pregnant woman, 19, on Southwest Side