A teenager who attacked two fellow pupils with a hammer while they were asleep at a private school boarding house had researched serial killers and what happened to children found guilty of murders, a jury has been told. The boy, who was 16 at the time, sent one of his alleged victims an image of a character from the horror film The Texas Chainsaw Massacre holding a hammer, Exeter crown court heard on Monday. He is said to have been good friends with the boy but fell out with him when he thought he had laughed at him as he worked on a school project and began treating him “horribly”. The defendant, now 17, allegedly attacked the two boys, who were 15 and 16, with one or more claw hammers. The jury has heard it was “astonishing” they survived their head and body injuries and both had suffered long-term consequences. He also allegedly attacked Henry Roffe-Silvester, a staff member who heard the commotion at Blundell’s school in Tiverton, Devon, and went to investigate. The 16-year-old, who cannot be named, has denied three counts of attempted murder and claimed he was sleepwalking after watching horror films, and had hammers because the films meant he needed to protect himself against a zombie apocalypse. James Dawes KC, prosecuting, said the defendant researched questions such as: “What happens if you hit someone on the head with a hammer?” and about attacking people while they slept, the jury heard. In the months before the attack, he allegedly searched for information about child serial killers, whether young people went to jail and investigated how respected serial killers were in prison. He is also said to have investigated if life imprisonment or the death penalty was better. A member of staff described the alleged attacker as “polite, personable, popular and hard-working”. But the court heard that in the months before the incident in the early hours of 9 June last year, he became hostile towards one of the victims because he believed he had laughed at the defendant during a class. The alleged victim said he and the defendant had been good friends but the defendant began acting horribly towards him and would smash up his possessions with hammers, and use his staple gun to fasten his things to a table. He also sent the image from the film The Texas Chainsaw Massacre and another showing an exposed brain. The jury heard that a staff member had heard a rumour that some boys were keeping hammers in their rooms and demanded they be handed in. Dawes said: “As a result of his demand, [the defendant] handed in a hammer. Asked why he had one he said he had bought it as it was cheap.” The court heard there was a rule at the school where the pupils had to give in their phones and tablets at 9.30pm, but the defendant had not handed in his tablet and was using it just before the alleged attack. In police interviews the youth answered “no comment” to all questions, as was his right, Dawes said. But the barrister said: “There is evidence about what he may have been thinking about prior to this attack. He had motive, he had planned something like this, he had thought about this in advance.” He said the defendant was not sleeping or dreaming at the time but was awake because he was using his iPad right up until the attacks started. The jury also heard that the defendant searched the internet for “rampage killers” and “school massacres” and looked up the killer Arthur Hutchinson on Wikipedia and used his name for online profiles. Dawes told the jury one of the defendant’s two victims described him as having a “locked weapon drawer” containing four hammers, screwdrivers, a staple gun and a piece of broken mirror. Another pupil told police that he knew the defendant had bought a hammer cheaply from a hardware shop. It was also claimed by another student that one of the teenage victims had a hammer in his room for his own protection. Some weeks before the alleged attack, a pupil said they heard a commotion in the room where the attacks later happened and saw the defendant holding a hammer before putting it under his mattress. He claimed he had permission to keep it. The jury was told that a short time before the alleged attacks the defendant viewed a report of a French playground knife attack.