(CNN) -- A 17-year-old Connecticut high school student pleaded not guilty Wednesday in the slashing death of a classmate in a school stairwell in April, a court official said.
Christopher Plaskon appeared in Milford Superior Court, where he waived his right to a probable cause hearing and elected to be tried by a three-judge panel rather than a 12-member jury, according to clerk Linda Kautzner.
His attorney, Richard Meehan Jr., told CNN that he is considering a mental health defense.
Plaskon is suspected of slashing classmate Maren Sanchez, 16, at Jonathan Law High School in Milford on April 25. He was 16 at the time.
A witness saw Plaskon on top of the victim and tried unsuccessfully to pull him away, according to a probable cause statement in the case. Another witness allegedly saw him discarding a bloody knife in a school corridor.
The state medical examiner's office concluded that Sanchez died from "stab wounds to the trunk and neck" and ruled the death a homicide.
Though the motive remains under investigation, police were looking into whether the boy was angry after Sanchez rejected him as a prom date.
"I did it," Plaskon allegedly told a school police officer in the principal's office moments after the crime, according to the probable cause statement. "Just arrest me."
Plaskon was ordered held on $3 million bond in April. He was charged as an adult and faces 25 to 60 years in prison if convicted.
His next court appearance is July 30, Kautzner said.