Temple Terrace police have charged a 35-year-old Granville Ritchie with the murder of 9-year-old Felecia Williams.
The announcement came at a Friday news conference.
The girl's body was found floating near Courtney Campbell Causeway in May.
Police had named Ritchie as a suspect several months ago, but he was not charged until now. He has been jailed since May on unrelated charges.
Investigators said Ritchie and Eboni Wiley picked up Felecia and went to the Doral Oaks apartments in Temple Terrace.
Wiley then left the girl alone with Ritchie.
The girl was beaten and sexually assaulted before being strangled to death, investigators said.
Ritchie then put her body in a suitcase and loaded it into his car.
Following the murder, Wiley was arrested for providing false information to law enforcement and has pleaded not guilty.
Ritchie is charged with first-degree murder, capital sexual assault and aggravated child abuse..