A 19-year-old Chicago pregnant woman missing since late April was found murdered after her baby, who was found alive, was ripped from her dead body, authorities said.

The newborn was found when paramedics responded to a call of a baby in distress on April 23, the day Marlen Ochoa-Lopez went missing after arranging to pick up baby clothes from someone she met in a Facebook group, a family spokeswoman told NBC Chicago.

The Cook County medical examiner's office confirmed that a body found near where paramedics found the baby had been positively identified as that of Ochoa-Lopez. The cause of death was homicide by strangulation, it said.

Marlen Ochoa-Lopez in an undated photo.

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

He confirmed that the infant was in grave condition.

Cecilia Garcia, a spokeswoman for the family, told reporters Wednesday that DNA was used to confirm that the child was Ochoa-Lopez's.

"It's a blessing that we found Yadiel, the baby, that's the name of the baby that Marlen had chosen," she said.

Ochoa-Lopez was nine months pregnant when she went missing after she was last seen leaving the Latino Youth High School, where she had been taking classes.

Garcia said Ochoa-Lopez had arranged to pick up baby clothes on the day she disappeared, plans she had made through a Facebook group called "Help A Sista Out."

A baby was forcibly removed from the body of Marlen Ochoa-Lopez, who was reported missing three weeks ago, in Chicago.

Ochoa was supposed to pick up her 3-year-old son from day care later that afternoon, but she never showed up, her family said, according to NBC Chicago.

Chicago police told NBC News in a statement Wednesday that they were interviewing people connected to the missing persons case but could not comment further.

NBC Chicago reported Thursday that three people were being questioned in the case.