It's been more than two years since 19-year-old Christopher Plaskon of Connecticut stabbed one of his classmates to death on prom night after she rejected his invitation to be his date. On Monday, Plaskon was sentenced to 25 years in prison for the murder, according to NBC Connecticut.

Plaskon was found guilty of stabbing the victim, 16-year-old Maren Sanchez, in a stairwell of Jonathan Law High School where the two were students. Plaskon had asked Sanchez to attend their prom with him in 2014, and was upset when she turned him down, NBC Connecticut reported. 

The Hartford Courant reported that when police arrived at the scene of the crime in 2014, Plaskon said, "I did it. Just arrest me." The Courant further reported that before his trial, Plaskon wrote a letter to his father from the juvenile detention center where he has been serving time, saying the reason he "did what he did" was because he had been hearing "voices."

In December of 2015, a friend of Plaskon's revealed Plaskon was so upset about Sanchez turning him down for prom because she was seeing someone already, that he had said he didn't mind if she wouldn’t mind if Sanchez "was dead or hit by a bus," the Milford Mirror reported.

NBC 4 reported that Plaskon will remain in the Manson Youth Institution in Cheshire, Conn. until he turns 22, after which he will be transferred to an adult prison. He will be eligible for parole in 13 years. 

Connecticut State Attorney Kevin Lawlor did not immediately reply to Complex's request for comment.