Wednesday, the Cook County Medical Examiner's Office said remains found at a home on West 77th Place were identified as Marlen Ochoa-Lopez.
She was reported missing three weeks ago and was nine months pregnant when she disappeared.
Officials said her cause of death was ligature strangulation. Her death has been ruled a homicide.
Police said three persons of interest that lived in the home remain in police custody. Police returned to the home late Wednesday night, at one point inspecting, a fire pit in the backyard.
Ochoa-Lopez's loved-ones have been left heartbroken and horrified.
"Why did these people, why did these bad people do this, she did nothing to them," said Yovani Lopez, her husband. "She was a good person."
WATCH: Husband speaks about Marlen Ochoa-Lopez's death
The family said they believe the pregnant teen was lured to the home through a Facebook post promising free baby items.
"It just seems surreal, like you see this stuff on movies," said family spokesperson Cecilia Garcia.
RAW VIDEO: Missing pregnant teen's remains found near Chicago home
On the day Ochoa-Lopez vanished, the fire department went to the home after a woman said she'd given birth.
"The caller gave birth 10 minutes ago," a 911 dispatcher tells the Chicago Fire Department. "Forty-six years of age. The baby isn't breathing. The baby is pale and blue. They are doing CPR."
That baby is now fighting for his life at Christ Hospital in Oak Lawn.
"The detectives went to see the baby, get the DNA testing, and confirm that that is Marlen's baby," Garcia said.
RELATED: Persons of interest questioned about pregnant teen missing 3 weeks
A person who didn't want to be identified said that woman from the home, one of three people being questioned, used to babysit her infant, until she began acting strangely.
"She told me how she was getting really attached to the baby, how she couldn't wait to be a mom again," the woman said.
Police have yet to name the three persons of interest and what charges they could be facing.
Ochoa-Lopez had previously been identified as Marlen Ochoa-Uriostegui. Uriostegui is her mother's name. Both police and the Cook County Medical Examiner identified her as Marlen Ochoa-Lopez.
As for the baby fighting for his life, Ochoa-Lopez's family said he has been named Yadiel.
Ochoa-Lopez's aunt said they are hoping to set up a GoFundMe campaign to help with expenses soon, but warned that the campaigns currently listed on GoFundMe for the family are not by or associated with them, and warned the public not to donate.