The teenager, who murdered his tenth standard classmate in the school compound at Muttar in Alappuzha, was inspired by the action packed Rambo series of veteran Hollywood star Sylvester Stallone, the police said on Wednesday.
The student, who was arrested on Tuesday, confessed that he had a great liking for Hollywood action thrillers, particularly those of Stallone, said the police.
The 15-year-old boy, who was staying with his father and stepmother, told police that he used to carry a knife along with him even while going to school.
The motive behind the murder of his classmate Lejin Varghese was to avenge a petty clash between the two when they were in the ninth standard, police said.
The school had opened for vacation classes on Monday. After classes were over by 11.30 am, the boy told the police that he took his classmate to the bathroom, hit him and slit his throat with a knife and a piece of broken glass.
To ensure that Lejin did not survive the ordeal, he hit him with a granite piece several times, the boy told the police.
The boy then went to a church and then to Ambalapuzha. He was arrested from the Changanassery railway station.
The relatives of slain Lejin, who hails from a poor family, began searching for him when he failed to return home. His body was found in the school compound on Monday.