Rawat has been called by the CBI to join the probe on Monday, sources said.
The inquiry was registered on the recommendation of the state government and the notification was issued by the Centre. The state is under President's rule.
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Two days before Rawat was to face vote of confidence on March 28, nine rebel Congress MLAs, led by former chief minister Vijay Bahuguna, had alleged that they were offered bribe by Rawat for support during the floor test in the Uttarakhand Assembly and released a video of the "sting" operation.
The sting CD made by the editor-in-chief of a private news channel and circulated by the nine Congress rebels who created a political crisis in the state by siding with BJP in the Assembly, purportedly shows Rawat negotiating a money deal with the journalist to buy the support of MLAs who had revolted against him.
Rawat, who had been insisting that the sting was fake, last week virtually admitted his presence in the controversial sting CD, but said it was not a crime to meet a journalist or an MLA and dismissed the conversation shown in the video as "meaningless".
Alleging that the sting operation and the CBI probe into it were part of a "criminal conspiracy" by BJP to topple an elected government, he dared Prime Minister Narendra Modi and BJP chief Amit Shah to put him in jail if he is found in the wrong.
Claiming innocence, Rawat had said if anything in the CD showed he made an offer in cash or kind in exchange for the support of disgruntled MLAs, he was ready "to be hanged" in public.