Two men were also arrested for what police say was failing to act to prevent bodily harm.
One of the women arrested Wednesday has been booked on preliminary charges of physical abuse of a child, though charges could change as the investigation continues. That same woman was sentenced to 18 months in prison in 2003 for involvement in the death of 1-year-old Bryan Alston. Reports show the woman stood by as two of her family members beat the baby, using him like a punching bag.
As for the 7-year-old, police are trying to learn more about the injuries leading up to his death.
"To hear something like that, it's just real devastating," said Victor Diaz, who lives in the building where the family lived.
He says police came to his apartment Tuesday asking questions about them.
Diaz says the family only recently moved in, but he had seen the mother with at least two young boys on occasion.
"Her children was like happy," said Diaz. "Her older son was happy, I always see him walking to school."
He says he believes the woman's younger son had some kind of physical handicap. But he never noticed anything that would make him think they were in danger.
"You know it's kind of hard explaining this to my children when they see these kids," he said.
Lauri Scales lives across the street and saw police and the medical examiner's office in her neighborhood. She didn't know what happened until the day after.
"I don't even know my grandchildren might have been playing with that kid at one time or another," she said.