The man who stabbed sixth-grader Sathi Khatun in Chapainawabganj town on Wednesday was surprised, during police interrogation, to hear that the girl survived the attack.

“The girl is still alive? How can that be!”

Monirul Islam, 25, of Railbagan area was arrested Wednesday evening for stabbing the schoolgirl. His rants were overheard by bystanders and Sathi's family members as he was being taken to police interrogation the same night.

Sathi's father Abdus Samad filed a case naming Monirul after he waylaid Sathi's rickshaw and stabbed her while she was going to school Wednesday morning.

A court sent Monirul to jail custody in the case yesterday.

Monirul is an accused in three other cases – one for stabbing Sathi's brother five years ago, two for mugging and drug peddling over recent years.

While in police custody, Monirul talked about Sathi's and expressed despise for himself for failing to kill her, Manjur Rahman, OC of the town's Sadar police station, said.

“She should be dead. I stabbed her to kill her. I wanted her family to learn a lesson,” the OC quoted Monirul as saying.

Monirul also told the police that he had taken an oath to kill the only daughter of the family since he was accused of stabbing her eldest brother in 2013 and had to go to jail for that, said the police officer.

Sathi's mother Selina Begum has expressed her fear and concern over Monirul's threats even while in police custody.

“I heard he was boasting of stabbing Sathi when police caught him from Horipur," she said. “If he is showing so much anger while in custody, what will he do when he is released?" she asked while talking to The Daily Star.

Other members of Sathi's family also heard Monirul's words while the police were taking him to the police van, she said.

Meanwhile Sathi, who was stabbed in four different parts of her body, underwent a five-hour surgery on Wednesday night at RMCH. She is now recovering, RMCH director Brig Gen Jamilur Rahman said.