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 Tushi, 15 -- a 10th grader of Tarash Government Girls School.

Bikash was a younger son of Kalicharan Sarker in the area, one of two brothers and five sisters in his family. His elder brother Prakash Sarker, a vice-president of Upazila Awami League, lived in the house beside where Bikash resided.

According to the relatives, the two brothers had conflict of interest over family properties.

Following the murders, the elder brother of Swarna, Sukomal Chandra Das filed a case with police as plaintiff.

SP Mandal said Bikash’s phone was taken off him after finding his body and a conversation between the uncle and his nephew on the phone revealed the intention of murder.

“After his father died in 2021, Rajib and Bikash began trade of food grains together. Bikash invested Tk 2 million. At different stages Rajib paid his uncle around Tk 2.6 million including profits.”

“At the beginning of this year Bikash demanded another Tk 3.5 million from Rajib. On Jan 22, Bikash pressed Rajib for paying the money within the following seven-eight days.

“Bikash also reprimanded Rajib’s mother over the matter. Rajib then failed to come up with the money and planned the murders.”

SP Mandal mentioned that Rajib called his uncle on Saturday afternoon to visit him to “pay off the money”. Bikash was not at home at that time and asked Rajib to visit his home to give the money to Swarna.

“After Rajib went to their home, his aunt went downstairs to a shop at one point. Rajib then hit his cousin Paramita in the head with an iron rod and later slit her throat to ensure that she was dead.”

“After his aunt returned home, Rajib lynched her and slit her throat to kill her as well. When his uncle Bikash returned home after a while, Rajib similarly killed him as well. He then dragged the bodies to the bedroom, locked it up and fled to Ullapara,” Mandal continued.

“Rajib was then apprehended based on his conversation with his uncle over the phone and he confessed to his crime.”

The rod was later recovered from a pond following information provided by Rajib. The bloodied sharp object was found at his home.

Rajib was sent to prison through a court order in the afternoon.

The bodies were handed over to relatives after autopsy on Wednesday evening.