Hyderabad, Nov 6 (IANS) : A former Congress Party member of parliament, his wife and their son have been arrested and sent to jail in Telangana's Warangal town in a case relating to the death of the ex-MP's daughter-in-law and three grandsons, police said.

Siricilla Rajaiah, his wife Madhavi and son Anil Kumar were arrested late Thursday and produced before a magistrate who sent them to judicial custody for 14 days.

They were later shifted to Warangal central jail.

The three were in police custody since Wednesday when charred bodies of S. Sarika and her sons were found in Rajaiah's house in Warangal.

S. Sarika and her three sons -- Abhinav (seven), Ayan (three) and Sriyan (three) -- were burnt to death in the fire. The cause of the fire is still under investigation.

On a complaint by Sarika's parents, police registered a case against Rajaiah, his wife and their son for harassment and abetment to suicide. The Police also booked a case of suspicious death.

Sarika's relatives blamed ex member of parliament, his wife and son for the deaths.

They cited a case booked against them in the past for harassing Sarika for dowry and Anil's extra-marital affair with a woman.

Police said they were investigating the case from all angles to reach to a conclusion if it was suicide or a murder.

Food samples collected from Rajaiah's house were also sent for examination to find out if Sarika and children were poisoned before burning.

Rajaiah was elected from Warangal in 2009 but lost last year.

He filed nomination papers for the by-election on Monday but told the party leadership after the tragedy that he was opting out of the race.