The 15-year-old boy who is thought to have stabbed teacher Ann Maguire to death at Corpus Christi Catholic School in Leeds has allegedly been found to have a Grim Reaper drawing on his Facebook page.
Classmates have since described the alleged killer as a loner, who did well in all subjects apart from Spanish (the subject in which he allegedly murdered his teacher).
They also said that the "outcast" pupil had seemed increasingly troubled in recent months.
Speaking to the Mail Online, one former student said: "He was apparently suicidal and had tried to kill himself several times.
"He used to say he was being bullied and he was really weird. He was really quiet though and didn’t say much."
Another added: "He had gone through stages of depression and used to be on anti-depressants.
"He was really clever and always got top grades. He was fine in everything apart from Spanish."
Detective Superintendent Simon Beldon, of West Yorkshire Police, said the 15-year-old suspect arrested on suspicion of murder remains in custody.
He will be questioned by officers "at some point during today".
"Given his young age, this is a process which needs to be handled very sensitively"
Speaking at a press conference outside the school, he said: "Given his young age, this is a process which needs to be handled very sensitively, and may take some time to complete.
"The pupils who witnessed this incident are still being interviewed by specialist officers and are very experienced in dealing with child witnesses and will ensure that their safety is paramount.
"This is clearly an unprecedented and tragic incident which has left the school and wider community in a state of shock."