The Calcutta High Court Wednesday directed the CBI to probe a murder case in West Bengal's Birbhum district in which a leader of the ruling Trinamool party is allegedly involved.The court of Justice Harish Tandon directed the Central Bureau of Investigation (CBI) to investigate all aspects of the murder of Sagar Ghosh, an independent panchayat member, that took place in Birbhum district in July last year.Ghosh was killed days after Birbhum Trinamool president Anubrata Mondal gave an inflammatory speech inciting party workers to resort to violence against independent candidates and hurl bombs at the police if they were prevented.The court also said the investigation by the Special Investigation Team (SIT) headed by the director general of West Bengal Police was "tainted by extraneous influence".While Mondal was named in the first information report by the victim's family, the SIT dropped his name from the charge sheet that it filed before a court in Birbhum which is hearing the murder case.The CBI has been directed to update the court about its investigation from time to time.Alleging that the state police tried to shield the perpetrators, Ghosh's son Hriday filed a petition before the high court, seeking a CBI probe.