After registering the case, the CBI started a search operation at a number of locations in Mumbai, they said.
On March 25, Param Bir Singh filed criminal public interest litigation seeking a CBI probe against Deshmukh who, he claimed, had asked police officers, including suspended cop Sachin Waze, to extort Rs 100 crore from bars and restaurants.
Singh had initially approached the Supreme Court, alleging he was transferred from the post of Mumbai police commissioner after he complained to Chief Minister Uddhav Thackeray and other senior leaders about the "corrupt malpractices" of Deshmukh.
The apex court had termed the matter as quite serious but asked Singh to approach the high court.