Delhi Deputy Chief Minister Manish Sisodia's OSD Gopal Krishna Madhav was arrested based on information provided by a middleman who allegedly collected bribes from transporters on his behalf, officials said on Friday.
The probe agency arrested the officer and middleman Dheeraj Gupta on Thursday, two days before the Delhi elections.
During the questioning, Gupta claimed that he was collecting Rs 2.26 lakh as bribe for Madhav, a Delhi Andaman and Nicobar Island Civil Service officer in trade and tax department.
Based on the information, the CBI arrested Madhav in a late evening operation on Thursday and immediately took him to the agency headquarters for questioning.
Gupta has been sent to judicial custody by a special court while Madhav will be produced before the court on Friday, they said.
Sources said the agency has not found Sisodia's involvement in the case so far but a probe is on.
Madhav was posted in the office of Sisodia in 2015, they said.