Mario McNeill, 29, is charged with first-degree murder, first-degree rape and kidnapping.
He's accused of taking Shaniya from her mother's home in the Sleepy Hollow Mobile Home Park on November 10.
Surveillance video captured images of McNeill carrying Shaniya into a Sanford hotel. Her body was found dumped just outside Sanford.
McNeill's attorney Allen Rogers says he's stepping aside because he feels the state defender office could provide more resources to work the case than he could.
Shaniya's mother, 25-year-old Antoinette Davis, is charged with human trafficking and child abuse involving prostitution in the case.