The rape occurred in a music storeroom at a high school on Dec 15.
The young woman, who has since died from injuries sustained in the attack, was the leader of the school's traditional pong lang band dance troupe. She was beaten unconscious and raped, and was pronounced dead from severe head injuries at Sappasit Prasong Hospital in Muang district on Monday.
Police received a report that DNA samples taken from the 17-year-old suspect matched traces found on the victim's body.
He has denied any involvement in the crime. Police are questioning him and have yet to lay any charges.
The suspect had been expelled from the school for misbehaviour.
He worked as a sound system labourer, and was working on the school band's sound system on the night of the rape, police said.