Closing arguments are set for Friday in the trial of a Massachusetts teenager charged with raping and killing his math teacher.

Prosecution rested their case against 16-year old Philip Chism on Wednesday.

Superior Court Judge David Lowy told jurors that lawyers on both sides would likely deliver closing arguments Friday. He says deliberations could start later that day.

Chism is charged with rape and murder in the October 2013 slaying of 24-year-old Danvers High School teacher Colleen Ritzer on school grounds.

His lawyers admit that Chism, who had recently moved to Danvers from Clarksville, Tennessee, killed Ritzer. But they say he was legally insane when he strangled Ritzer, stabbed her with a box cutter and then used a large trash bin to haul her body into the nearby woods.