(AP) — A 17-year-old Omaha teen has admitted killing his 16-year-old ex-girlfriend as part of a deal with prosecutors.

The teen pleaded guilty Tuesday to second-degree murder in the May 2012 death of Melanie Koontz. Previously, he had been charged with first-degree murder and using a weapon to commit the crime.

Koontz’ body was found in an Omaha creek. Prosecutors say she had been strangled.

The boy will be evaluated by a psychologist before he is sentences on Nov. 6. He faces 20 years to life in prison.

The Associated Press generally doesn’t identify juveniles accused of a crime.