Polk County investigators arrested a 19-year-old for the murder of a classmate, but said they are still looking for another suspect.

Eyewitness News first reported last month when Alicia Barnett's body was found on the Chain of Lakes Trail in Winter Haven.

Investigators said Antonio Callaway and another person set up a drug deal with Barnett, then shot and killed her.

Callaway and Barnett were classmates at New Beginnings High School in Winter Haven.

The principal said she was shocked to hear about the arrest.

"When you commit your life to helping others seek another chance, and that's what all of our staff do here in the building, and you find out that their not actually doing that, it is disappointing and it is disheartening," Ashley Wright, New Beginnings Principal.

Investigators said they used cell phone communications to connect Callaway to the murder.

The investigation is still ongoing.