Authorities ruled the deaths homicides and autopsies performed Friday revealed that heat was a factor.
Chicago's top cop is warning parents the deaths are a stark reminder of how dangerous extreme weather can be.
The state's attorney has charged the mother, Regina Lofton, 21, with two counts of endangering the life of a child, a class three felony that could carry up to 12 years in prison. The charges are adding more difficulty to the tragic loss the girls' family is dealing with.
Lofton was overcome with emotion Thursday night shortly after finding her twin 13-month-old girls unresponsive in their bedroom. Family members say Kimora and Kimari Roberson were happy, healthy children. Their deaths came as a shock.
"Everybody of course is heart broken about these two innocent 1-year-old baby girls who didn't get any chance at life at all," said Cynthia Hike, aunt.
Police took their mother to the station to get more information about the circumstances and when the medical examiner's autopsy Friday determined the girls died of hyperthermia- or elevated body temperature - due to parental neglect police charged her with two counts of endangering the life of a child.
"That is a senseless tragedy and I think it's a very stark reminder that these type of extreme heat conditions or cold conditions can prove deadly for the very young and the very old," said Superintendent Jody Weis, Chicago Police Department.
No one came to the door at the home when ABC7 stopped by Friday night. Family members say the children's father lives at the house with their mother and other relatives are frequently at the house as well. Those who know her describe the young mother as loving and attentive. The medical examiner, however, rules the deaths homicides saying the babies weighed just 13 pounds each.
"On top of that tragedy you add more by accusing the mom, I mean, just going out of her way to harm these kids, I don't see it," said Hike.
"It's certainly the responsibility of adults to make sure that we don't inadvertently or advertenly...put young people or elderly in situations where they are prone to be being damaged, injured or even killed form extreme weather conditions," said Supt. Weis.Regina Lofton is scheduled to be in bond court Saturday morning. The Department of Children and Family Services has also been called to investigate and to look after Lofton's other children. They say they have had no prior contact with the family.