Istanbul police said on Sunday that forensic experts had not finished their autopsy on the victim, Sarai Sierra, but that it was "clear" the head injury caused her death.
The 33-year-old was last heard from on Jan. 21 - the day she was scheduled to fly home from a vacation.
Her body was discovered Saturday night near the remnants of ancient city walls.
The mother of two reportedly still had her earrings and a bracelet when she was found.
Turkish state-run news agency NTV says 15 people have been detained for questioning in the case.
The Associated Press contributed to this report.