In a major development in the Palakkad double murder, the accused has admitted that he murdered the elderly couple as they were a threat to his relationship with their daughter-in-law.

Sadanandan, an Ernakulam native, was produced at the couple's house in Tholanur for evidence collection on Thursday. The police have recovered the weapons used for the murder from a well in the premises, while a bag containing some clothes was recovered from a thicket near the house.

Also read: Elderly couple found brutally murdered in Palakkad

Sheeja, the couple's daughter-in-law who was present at house at the time of the murders, is also understood to be involved in the act. She is currently hospitalised but is expected to be taken into custody on Thursday night.

Reports claim that Sadanandan and Sheeja met each other four months ago and grew close. Sheeja had allegedly promised to make him the caretaker of the house, if he helped her get rid of her in-laws.

The murders happned on Tuesday night and came to light the next morning when a woman arrived to deliver milk at the couple's home. Swaminathan, 72, an ex-military personnel, was found with his throat slit, while his wife Premakumari, 62, was found smothered with a pillow.

Sheeja was found at the murder scene with her hands and legs tied but with no injuries, leading the police to suspect her involvement. Sadanandan was arrested from the Palakkad bus stand on Wednesday evening.