New Delhi, June 22 (IANS) The murder of a young husband and wife in a suspected case of honour killing here took a new twist after a cousin of the woman was also found shot dead Tuesday.

Shobha, 22, was found dead inside a parked black Santro car used by her brother Mandeep, a suspect in Sunday's twin murder of Kuldeep (26) and his wife Monica, 23. The couple had been murdered Sunday.

Like Kuldeep and Monica, Shobha too was found dead in the middle-class neighbourhood of Ashok Vihar in north Delhi.

Police discovered Shobha's body after getting a telephone call Tuesday morning. "A used cartridge has been recovered from the spot," an officer said.

"We think Shobha was killed the same day (Sunday) as there was a foul smell in the car," he added.

Police sources said there were three suspects -- Monica's brother Ankit, Mandeep and his friend Rahul. All three men are absconding.

"Apart from these three, we are questioning the family and friends of the murdered woman," the officer said.

Police sources said the murder saga had its origin in Monica's marriage with Kuldeep some years ago, much against the wishes of the girl's family.

Some years later Mandeep's sisters Shobha and Kushboo ran away from their home.

A bitter Mandeep blamed Ankit for their flight, saying the sisters had been encouraged by what Monica did.

While Kushboo got married, Shobha returned to their home.

Determined to avenge what they felt was their families' dishonour, Ankit and Mandeep finally decided to murder their sisters.

According to police sources, Ankit's sister Monica, her husband Kuldeep and Mandeep's sister Shobha were done to death, one after the other.

The police are now looking for the alleged assailants -- and the murder weapon.