A Connecticut teenager who fatally stabbed a classmate the morning of their junior prom because she turned down his invitation is scheduled to be sentenced.

A judge is expected to sentence 19-year-old Christopher Plaskon to 25 years in prison on Monday in Milford Superior Court.

Plaskon pleaded no contest to murder in March in the killing of 16-year-old Maren Sanchez inside Jonathan Law High School in Milford in April 2014.

Plaskon's attorneys have said he showed signs of psychosis and they considered an insanity defense.

Sanchez's parents filed a lawsuit accusing the school system of negligence, saying she told a guidance counselor that Plaskon was troubled and capable of hurting others. School officials have declined to comment.