Police said Shaniya was last seen alive with him on surveillance video taken from a Comfort Suites hotel in Sanford the same morning her mother reported her missing.
The girl's body was later discovered Monday in a wooded area about seven miles from the Sanford hotel on the Harnett and Lee County line.
Search warrants show investigators found children's clothing, blankets and DNA when they searched McNeill's Mitsubishi Galant and took away 11 bags of evidence.
McNeill turned himself in to police last week, and investigators say he confessed to taking the 5-year-old. However, McNeill's attorney told reporters his client would plead not guilty.
Shaniya Davis' 25-year-old mother, Antoinette, is also charged in the case. She is charged with human trafficking, prostitution and felony child abuse in her daughter's disappearance. Warrants say she provided her daughter with intent that the girl be held in sexual servitude.
Acquaintances say Antoinette Davis knew McNeill, because he dated her sister Brenda.
ABC11 Eyewitness News has confirmed Antoinette Davis is pregnant and jail officials say she is being kept separate from the rest of the prison population. McNeill also remains in jail.
However, more questions are being raised about McNeill's criminal background.
Just three weeks ago, McNeill was unconditionally released from supervised probation six months early.
"This is an offender who did well under supervision and met all the requirements," said Keith Acree with the Department of Correction. "The court reviewed the case and agreed it was eligible for early termination."
According to Department of Correction files, McNeill's criminal record dates back to July 2001, when he was charged with shooting three people in their car.
McNeill pleaded guilty to a lesser charge and was placed on probation.
The mother of two of those victims told ABC11 Eyewitness News she is still angry that McNeill was allowed to cut a deal.
"I'll never forget Mario's face," victims' mother Flora Green said. "They showed his face and I'm feeling guilty and been crying two days thinking of this."
Court records show since 2003 McNeill has been in and out or prison on a variety of charges, and often paroled.
While Department of Correction officials say even if McNeill was still on probation, it might not have prevented the crime.
Green says she thinks McNeill got off too easy.
"If they would have kept him in jail, those charges would have stuck," Green said. "It wouldn't have happened. That's how I feel."
Shaniya Davis' father
As the investigation continues, there are allegations that the 5-year-old's father could have done more to prevent her death.
Bradley Lockhart, a contractor who spends most of his time out of state, was working in Utah when Shaniya turned up missing.
Shaniya Davis was living in her father's $240,000 home in an upscale Cumberland County neighborhood before he sent her to live with her mother in the Sleepy Hollow Mobile Park. Antoinette Davis has a history of drugs and prostitution.
Tim Allen, who is taking care of Lockhart's 17-year-old daughter after her father kicked her out of his home, says Lockhart's girlfriend, Ty, was doing a wonderful job taking care of the 5-year-old for months before her death.
"Yeah she was well taken care of, just always had her hair done and smelling good, just like she was her own biological child," Allen said. "I don't know if he met somebody out in Utah and basically Ty just went away ... and just went downhill from there."
Meanwhile, sources say a preliminary autopsy on Shaniya Davis has been completed, though investigators have not released a cause of death or who killed her.