The parents didn’t see the note. Maheshwari had sent two previous notes already this month in the school handbook to the boy’s parents. The first, on February 2, just said “he does not perform up to the mark”. In the second, four days later, she wrote “...strictly warned, promotion doubtful...”. Police officials who spoke to the boy after the incident said he had decided to attack her after the second one.

Classmates say the boy, a student of Class IX-A at St Mary’s Anglo Indian Higher Secondary School, whom Maheshwari taught Science and Hindi, did not have many friends at the school or in his neighbourhood.

While his three sisters are all well-settled — one is a dentist, the other a software professional, and the third is doing an MCA — the boy was reportedly not good in studies and would be constantly scolded at home because of this.

In the past academic year alone, 13 adverse remarks were sent to the boy’s parents from the school, written by two others besides Uma; all but the last one seen and acknowledged by parents. The father runs a logistics firm and employs around 30 people.

After the second note indicated that he may not be moved to Class X, the boy bought a knife from a neighbourhood shop for Rs 20. “He was carrying it with him for the past couple of days, but did not get an opportunity to attack Maheshwari,” said an official at the Esplanade police station.

On February 9, a day after the third note, when Maheshwari was sitting in Class X-C classroom waiting for students to come for Hindi classes, the boy rushed in and stabbed her repeatedly. She was stabbed on her stomach, chest and throat, and when she doubled in pain, he stabbed her back.

As teachers, staff and students rushed to the classroom on the first floor hearing her cries and the alarm raised by students who were present in the room, the boy confessed how angry he was. Witnesses said he dropped the knife and walked out, still wearing his bloodstained school uniform. He was arrested a little while later from a nearby street. “When arrested, he did not deny or resist, nor did he display much emotion,” said an official.

Inflicted 10 major and minor injuries, Maheshwari later died at hospital.

Ironically, say those who knew the teacher, she was quite reserved herself. She stayed alone, apart from her husband — an employee of a private company — in her south Chennai home. Her daughters, around the same age as the boy, 12 and 16, stay in a boarding school. She used to visit them on Sundays.

Incredulity runs high in the narrow lanes of north Chennai, or Old Madras, where the boy lives. Working in a godown next door to his house, Ramu, a daily wager worker, said he had seen the boy grow up from a small child. However, they never spoke. “He is a quiet type who didn’t talk to anyone around here. Once he is back from school in the evening, he isn’t seen till the next morning,” he said.