CHICAGO (AP) — A missing pregnant woman whose body was found behind at home on Chicago's Southwest Side had been strangled, and her baby was hospitalized in "grave condition" after being cut from the womb after her death, police said.

The Cook County medical examiner's office identified the victim on Wednesday as 19-year-old Marlen Ochoa-Uriostegui and determined she died of ligature strangulation. Ochoa-Uriostegui was nine months pregnant when she disappeared April 23 after leaving her high school.

"We believe that she was murdered and we believe that the baby was forcibly removed following that murder," said Chicago police spokesman Anthony Guglielmi.

Ochoa-Uriostegui's body was discovered after several people were taken into custody at the home, according to authorities. No charges against those in custody have been announced.

Her family said they believe she went to the home after a woman on Facebook said she had a stroller and baby clothes, according to the Chicago Tribune.

"She was giving clothes away, supposedly under the pretense that her daughters had been given clothes and they had all these extra boy clothes," said Cecelia Garcia, a spokeswoman for Ochoa-Uriostegui's family.

Chicago Fire Department spokesman Larry Merritt told the Chicago Tribune paramedics were called to the home for a newborn with problems breathing on the same day the woman disappeared.

Guglielmi said investigators are interviewing the people taken from the home about the slaying of Ochoa-Uriostegui.

"We believe all of them played some role in this unspeakable act of violence," he said.