Days after a key accused in a case of violence in West Bengal's Birbhum allegedly died by suicide in CBI custody, state police filed a murder case against the officials of the central probe agency. Lalon Sheikh, one of the main accused in the violence that took place earlier this year at Bogtui village of Bengal's Birbhum district, allegedly died by suicide in CBI custody on Monday. A First Information Report or FIR registered by the cops name senior officials of the CBI for the "murder" of the accused. Sources say the agency will be challenging the FIR in the Calcutta High Court.