The promotion was cleared after the senior police officer got clean chit from the committee that probed his alleged involvement in the case, the sources said.
At present, Singh was working as Commandant First Battalion of the State Armed Police.
Bowing to pressure from within his party as well as the growing public discontent over the death of Rizwanur Rehman, the then Chief Minister Buddhadeb Bhattacharjee shunted out Kolkata Police Commissioner Prasun Mukherjee and four other senior police officers including Singh, then a Deputy Commissioner of Kolkata Police, for their alleged "intervention" in the case in October, 2007.
Rizwanur, a multimedia graphic designer, was found dead near the railway tracks on September 21, weeks after he got married to Priyanka, daughter of industrialist Ashok Todi.
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The Todi family and the police had allegedly mounted pressure on the couple to break the marriage. Police claimed it was a case of suicide while the family alleged that Rizwanur was murdered.
Kallol Ganai, who was working as DIG Murshidabad Range, has been asked to take over as Joint Commissioner of Police, Barrackpore Police Commissionerate.
The PWD Joint Secretary Osman Ghani has been asked to take over as Secretary State Election Commission, while Deputy Director of AYUSH under Health Department Goutam Ghosh would take over as Secretary to GTA in Darjeeling, the sources said.