A 23-year-old woman stabbed her brother-in-law to death after he attempted to rape her at their apartment in Madhavaram in the early hours of Friday.

The police have registered a case of culpable homicide not amounting to murder, and are unlikely to arrest the woman as she had acted in self-defence.

The Madhavaram police identified the deceased as Mathew Binuraj (33), a real estate agent working in Anna Nagar.

He resided with his wife, a nurse by profession, her sister and the couple’s eight-year-old son in a two-bedroom apartment in Madhavaram Milk Colony.

The woman, the youngest sister of the deceased’s wife and a third-year B.Com student at a private college in city, resided with the couple as they were her guardians following her parents’ demise.

According to the police, Mathew, who was an alcoholic, often attempted to sexually assault his sister-in-law but he was thwarted due to his wife’s intervention. Early on Friday, Mathew, who was under the influence of alcohol, entered the young woman’s room.

“When his wife intervened, he pushed her out of the room and locked the door. When he tried to rape his sister-in-law, she grabbed a knife and stabbed Mathew in the neck, killing him on the spot,” said an investigating officer.

The Madhavaram police have registered a case under Section 304 (culpable homicide not amounting to murder) of IPC that is likely be altered to one under Section 100 (when the right of private defence of the body extends to causing death).

In a similar case registered by the Oomachikulam police in Madurai on February 2012, a woman murdered her husband by attacking him with a cricket bat after he attempted to sexually assault the couple’s daughter in an inebriated state.

A court acquitted the woman after the police booked her under Section 100 of IPC.

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