Dhaka, Jan. 31 -- Police have arrested a youth, who is a relative of the husband, wife and child killed in Sirajganj's Tarash Upazila, in the murder case based on records found on mobile phone.

On Tuesday morning, the three were found dead on the third floor of a house at the municipality's Barowari Battala Mahalla.

The youth, Rajib Kumar Bhowmik, 35, was subsequently arrested that evening, said Superintendent of Sirajganj Police Ariful Rahman Mandal.

Rajib is the son of the late Biswanath Bhowmik and Pramila Rani Bhowmik. He is the nephew of the murdered Bikash Sarker, the officer said in a press briefing on Wednesday.

Police had recovered the bodies of Bikash, 45, his wife Swarna Rani Sarker, 40, and their only child Paramita Sarker...