Singh has asked his deputy Special Director Saleem Ali to supervise the investigation as part of "internal arrangement", CBI sources said.
When asked whether Home Ministry or Government has been intimated about the change, CBI sources replied in the negative saying it was just an internal arrangement and there was no requirement to inform anyone.
CBI sources said this has been an informal practise that officers who belong to a particular state are not given charge of probe related to those states but it is not a hard rule as Aarushi murder was probed by UP cadre officers during the time of the Director who was also from the same cadre.
They said the role of CBI Director is supervisory which does not deal with day-to-day investigation but seeing the political implications of the case and also that he had been the OSD to Munda, he has decided to recuse himself.
The poll for the Rajya Sabha scheduled on March 30 was countermanded following the allegations of horse trading and fresh elections were held on May 3 to fill up the two vacancies.
"This case was registered by CBI on a reference from the Election Commission of India with the directions of Hon