State investigators also began interviewing Cumberland County Department of Social Service employees.
The SBI became involved with the case after Fayetteville Police Chief Chief Tom Bergamine expressed concerns that detectives investigating Shaniya's murder were unable to obtain records from DSS.
The 5-year-old Fayetteville girl's body was found last month in woods near Sanford.
Mario McNeill is charged with first-degree rape, kidnapping and murder. Davis' mother, Antoinette Davis, is charged with human trafficking and child abuse involving prostitution.
As part of the investigation, police are looking into DSS's involvement in Shaniya's case.
Relatives told ABC11 Eyewitness News last month that DSS had been called to the Davis home on several occasions, but neither Shaniya or her brother were removed from the home.