Cuttack, Oct. 10: The crime branch today found two knives used in the Astaranga quadruple murder case.

The breakthrough came after interrogation of the key accused couple - Himadri Sekhar Das, 33, and his wife Aaisha Begum, 29, who were taken to the spot of the crime.

The accused had used the knives to stab Mallick, a retired district inspector of schools, his wife Nirmala, 45, and two children - Pranati, 10, and Saswati, 4, to death in the house on September 22. The bloodstained knives were hidden inside the house.

Acting on information given by the accused couple, who the cops arrested from Silchar in Assam on October 8, the police also traced the motorcycle belonging of victim from a place, though they refused to disclose it. Police sources said a mobile phone belonging to the deceased, 68-year-old Dinanbandhu Mallick, was also recovered from Silchar.

The assailants procured both the weapons and used them to slit the throats of Mallick and his family members. The weapons will shortly be sent for forensic examination.

Today, the couple were taken to the deceased's house to recreate the crime scene.

Additional director-general of police (crime branch) B.K. Sharma earlier told reporters that the accused couple had been going through financial trouble and sought monetary help from the deceased. The couple, who had come to Mallick's house with the knives, killed the four after Mallick had refused to provide monetary assistance to them on September 22.

They fled with a few gold ornaments, one mobile phone and a motorcycle belonging to the deceased after committing the murder. They are alleged to have sold the ornaments at Rs 30,000.

The probe revealed that Himadri and Aaisha, who hailed from West Midnapore in Bengal, had been staying in Raipur, Chhattisgarh, for a few years. The couple had a tough time in making ends meet and subsequently conspired to kill Mallick and loot cash and other valuables from his house. The crime branch is also probing into different angles of the murder as it is suspected that the family could have been eliminated over a property dispute.

A local court today granted the crime branch a four-day remand of the accused couple, who were on transit demand.

The probe also revealed that the accused couple knew one of the deceased's relatives. Earlier, the duo had visited Mallick's house twice and were aware of the fact that he lived in the house with his wife and two minor children. "A close relative of the deceased had introduced the accused couple to the family. Now, he is also under scanner. We suspect the role of a few others and hope to shortly complete the entire investigation by arresting them in connection with the case," said a senior crime branch official.

Following a public outcry, the state government had ordered for a crime branch probe on September 24. The investigating agency had formed five special teams to nab the assailants.

Sources in the crime branch said that nearly 25 officers were working on the case while various teams had moved to other parts of the country, including Raipur and Bhopal and the Northeast, to collect clues and evidence in the case.