A 16-year-old boy, who allegedly strangled a nine-year-old girl to death at her house and then tried to set her body ablaze in a gruesome crime in Gurugram on Monday, confessed that he planned to steal jewellery from the victim’s house in order to pay off debts he incurred in online gambling, but committed the murder in the “spur of the moment” after the victim caught him stealing and raised an alarm, police said on Tuesday.

The accused told investigators that he lost ₹20,000 in online gambling and borrowed money from a friend to pay it off. It was this friend’s pressure to repay the debt, police said, that prompted him to launch his elaborate plan, which ended in the murder of the nine-year-old girl.

The accused was presented before the juvenile justice board (JJB) and taken into two-day protective custody. Investigators said they will take permission from court to take the minor’s DNA samples.

Naveen Kumar, Gurugram assistant commissioner of police (ACP), said that the boy told investigators that he frequently used his mother’s cellphone for studies. However, he started using it to play online games at night and lost ₹20,000 at one point. He then borrowed money from his friend to repay the debt. But he was struggling to return the loan to his friend.

“He told us he was under pressure to repay the money. After unsuccessfully trying stealing from a lot of places, he decided to steal jewellery from victim’s house since he knew which cupboard contained her jewellery and he was aware of where the keys were kept,” he said.

The boy’s mother and the victim’s mother, both residents of an apartment complex in Sector 107 on Dwarka Expressway, were acquainted, said police, adding that the 16-year-old used to play with the latter’s two-year-old son. In this vein, on Monday morning, the teenager asked the victim’s mother if he could play with her son, and took him to his house, two buildings away.

Kumar said so far, the boy has repeatedly changed his statements and when he was asked about his friend, he refused to reveal any name.

“We scanned CCTV footage of the area. On the day of the crime, he is first seen walking towards his tower with the victim’s younger brother, and in the second, going back to the victim’s tower alone,” he said.

“He was desperate for money and on Thursday (June 27), he hatched a plan to visit the victim’s house since he knew that the victim’s mother often visited his house to meet his mother and left her two-year-old son there when she stepped out. According to his plan, he got the minor boy to his house, assuming that both mothers were engaged in conversation, and then slipped out to go to the victim’s house,” said ACP Kumar.

Police officers said he used ground naphthalene balls to quickly incinerate the body – a trick he learnt from a Hindi true-crime TV show to quickly dispose of the body.

They said that he had also identified a jeweller, to whom he intended to sell ornaments he was stealing.

Police said the boy had so far expressed no remorse. “When he removed the dupatta after strangling her, she started breathing again and got scared. He then strangulated her again, till she died and then quickly got naphthalene balls and camphor placed next to a temple in the next room and set her on fire,” he said.

The only regret the boy has expressed is that he was caught, said police.

Dr Deepak Mathur, forensic expert, Civil Hospital Gurugram said that the girl died of strangulation. “There were 50% burn injuries on her right side of the body and 10% on her left side. We have sent the vagina swab to FSL Madhuban but prime facie it does not look a case of sexual assault. As per protocol we have taken all samples for further verification,” he said.