After one of the prime accused persons in the violence in Bogtui village of West Bengal’s Birbhum district was found dead in the custody of the Central Bureau of Investigation, the ruling Trinamool Congress on Tuesday demanded an inquiry into the matter, ANI reported.

On March 21, eight people had died in Bogtui after their houses were set on fire following the murder of Bhadu Sheikh, a panchayat leader of the Trinamool Congress. Sheikh had succumbed to his injuries after unidentified people allegedly hurled bombs at him.

According to the chargesheet, the violence in the village was a retaliatory attack in response to the killing of Sheikh.

Lalan Sheikh, the prime accused in the case, was arrested by the Central Bureau of Investigation on December 4 and has been in custody since then. He was reportedly a close aide of Bhadu Sheikh and had been hiding in Jharkhand after the violence.

On Monday, Lalan Sheikh was allegedly found hanging in a washroom of an office that the central agency has set up in a guest house in Rampurhat area of Birbhu, according to PTI.

His family members claim that he died due to torture in custody. “When CBI brought him [Sheikh] home and also took him to his in-law’s house during the course of the probe, he could hardly stand,” his sister Samsunnahar Bibi told reporters. “They thrashed him mercilessly. He was not even allowed to drink water. We want punishment for CBI officers.”

The Central Bureau of Investigation has not yet released a statement on his death.

Trinamool Congress leader Madan Mitra linked the Opposition Bharatiya Janata Party with the death. “Everything is very mysterious,” he added. “The BJP leaders including Suvendu Adhikari and Dilip Ghosh had mentioned that something will happen in Bengal in December and Suvendu Adhikari had categorically mentioned the date as December 12.”

Mitra said his party will assist in the investigation of the matter. “If the prime accused is found hanging in CBI custody, how will the people have faith in the agency?” he asked.