"We have a lot of people … [who have] lost their jobs, who don't have health care, even children that are in homes don't get three square meals a day. But this man sits with guards protecting him, he's receiving free medical, free meals," Carey Lockhart-Davis said on CBS' "The Early Show" Monday.
Mario McNeill has been charged with first-degree murder and first-degree rape of a child. Authorities say Davis was strangled to death.
The 29-year-old McNeill was charged previously with kidnapping, with authorities saying he took Davis from her Fayetteville home. Her body was found Monday in thick underbrush off a rural North Carolina road after searchers spent nearly a week looking for her.
The girl's mother, Antoinette Davis, is charged with trafficking her daughter and child abuse involving prostitution.
More coverage of the Shaniya Davis case from Crimsider:
On Sunday, family members gathered for an emotional funeral service that even drew hundreds of strangers from around the country. A visibly distraught Lockhart-Davis, who helped raise Shaniya with the girl's father, Bradley Lockhart, said the experience has been "overwhelming."
"I spent a lot of special times with Shaniya and it's heartbreaking."
Lockhart-Davis said she's had to take down pictures of her niece because the reminders are too difficult for her and her family to bear.
"My children don't want to be home because that's an emptiness in here without her laughter."
Lockhart-Davis said she's "agitated" that McNeill, who is in custody under suicide watch, is now under state care.
"It disgusts me," she told "Early Show" co-anchor Maggie Rodriguez. "It bothers me a lot. And that's something I just don't understand."