The body of Marlen Ochoa-Lopez, 19, was found almost four weeks after she disappeared. (Representational)

Police in Chicago were questioning three people Thursday in connection with the murder of a pregnant teenager whose unborn baby was taken from her womb after her death.

The body of Marlen Ochoa-Lopez, 19, was found Wednesday, almost four weeks after she disappeared.

The Cook County Medical Examiner's Office said her death was caused by "ligature strangulation" and has been classified as a homocide.

The nine months pregnant teen was lured to the home of a stranger with the promise of free baby supplies and was murdered, after which her baby was cut out of her womb, according to local media reports citing authorities and family members.

The baby was reportedly in grave condition at a hospital and was not expected to survive.

Ochoa-Lopez's body was found in a trash bin near the home where police believe she was killed, according to WGN television.

Police spokeswoman Kellie Bartoli said detectives were questioning three people in connection with the case and that charges were pending.

Ochoa-Lopez was lured through a Facebook group for mothers by someone who offered her free baby clothes and a stroller, according to media reports.

The woman believed to have lured the teen later called emergency services to report a baby that was having difficulty breathing, the Chicago Tribune reported.