FAIRFIELD -- Fairfield police say they're working with the FBI in the search for the killer of a 13-year-old girl whose body was found in a park last week.

Police released few new details during a press conference Wednesday, but did repeat their request for help from the public, especially anyone who may have seen Genelle Renee Conway-Allen Thursday afternoon.

The teen was reported missing around 5:45 p.m. Thursday by her guardian at the foster home in nearby Suisun City where she lived. Police say her naked body was found a little before 7 a.m. Friday by a passerby.

The manager of a market located near a surveillance camera that took a photo of Genelle shortly before she vanished told police that a girl matching her description was outside his store.

Ibrahim Mohammad said that the girl said she was waiting for a ride when he asked.

"This has been a devastating tragedy for our family and community," the teen's family said in a statement released Wednesday. "We need to thank everyone for the outpouring of support at the memorial site."

After thanking police for working hard on the investigation, the family said they are still in a state of shock and asked for privacy.

"Thank you for your love and support during this difficult time," the family said.

In what police said was a photo taken minutes before she was last seen, the teen was wearing a gray sweater, blue jean-style leggings and a pink backpack.

Bloesch said police are not releasing information that might hinder the investigation, and that Suisun City and Fairfield police will investigate the homicide "in a professional, consistent and strategic manner" until the suspect or suspects have been identified, located and arrested.

Police also reminded parents to teach children what to do if they are approached or followed and to make every effort to escape and attract attention to themselves.

Anyone who saw Conway-Allen between Thursday afternoon and Friday morning is asked to call Fairfield police at (707) 428-7345.

The Associated Press and Bay Area News Service contributed to this report.