Kolkata, June 30 : A key CBI official of Kolkata Zone, who was heading crucial cases like post-poll violence and Bogtui massacre, has been transferred. Power corridors in West Bengal are abuzz with murmers of speculation since Thursday morning following the development. Deputy Inspector General in the Central Bureau of Investigation (CBI), Akhilesh Singh, who as the head of the agency's special branch in the Kolkata Zone was heading crucial probes like post-poll violence, carnage at Birbhum district's Bogtui village, murder of Congress councilor Tapan Kandu at Purulia's Jhalda, and rape-murder of a minor girl at Nadia's Hanskhali. He was mainly operating from CBI's special branch division located at the central government office (CGO) complex at Salt Lake in the northern outskirts of Kolkata. As per the transfer order, Singh has been transferred as deputy inspector general of CBI's newly operations special duty & research wing in New Delhi. CBI sources called it a routine transfer considering that Singh is slated to be promoted to the rank of inspector general shortly. However, some sections have already started raising questions whether his transfer at this juncture will impact the pace of investigation in these vital cases. Some of his colleagues, on strict condition of anonymity, said Singh's specialty was his methodical approach before beginning any investigation. They said that when the task of probing the post-poll violence came was given to him, the first thing that he did was to set up special camp offices in different pockets of the state considering that the different cases on this count are scattered over wide geographical locations. Singh is the second key CBI officer who had been transferred from CBI's Kolkata Zone. In the second week of the current month, the joint director in charge of the agency's anti-corruption wing, Pankaj Srivastava has been shifted out of Kolkata to New Delhi. Srivastava was in the overall charge of all the cases involving financial embezzlement like chit funds, Narada video tape scam, cattle and coal smuggling and most importantly, the West Bengal School Service Commission (WBSSC) recruitment irregularities scam. Srivastava was replaced by N. Venu Gopal, a 1995 batch Indian Police Service (IPS) officer of the Himachal Pradesh cadre. /IANS