Chloe Karl, 15, was reported missing on Saturday. She was last seen at a dance at Bay Port High School.
Investigators believed the teen was a runaway, but suspected she might have been in danger.
Her purse was found in a ditch along Hwy FF at Pine Tree Road, but her cellphone was not found in it. Investigators contacted the service provider to try to track the phone, and determined it had not been active since at least Sunday.
Investigators plan to talk to the teen on Friday about where she spent the six days she was missing.