MILFORD - Christopher Plaskon is due in court Friday, where police say he will be charged as an adult in the fatal stabbing of Maren Sanchez at Jonathan Law High School.
Police say Plaskon is being held under psychiatric care.
Court officials released documents on Tuesday detailing what police say were Plaskon's actions the day he allegedly murdered Sanchez. Police say a school officer who was already on duty at the time of the incident was called to the principal's office, where he saw Plaskon with bloody hands and clothing.
The officer then reportedly asked Plaskon what happened, to which Plaskon said, "I did it. Just arrest me." Police say the officer put Plaskon in handcuffs and then went to the stairwell where Sanchez lay after the stabbing.
Authorities say medical technicians worked to save the victim while she was taken to the hospital, and Plaskon was taken into custody.
The documents also describe how witnesses tried to help. Police say one witness saw Plaskon discard a bloody knife onto a hallway floor.
The report does not mention any motive, but students told News 12 the day of the incident that the attack may have been because Sanchez had told Plaskon she would not be his date for the junior prom.