A team from the I-T Directorate of Criminal Investigation joined sleuths of the probe agency in carrying out searches in at least 10 locations in Delhi and Gurgaon, sources said.
A farmhouse in South Delhi and another property in Delhi have been raided by the teams from where some documents have been collected, they said.
Authorities said the CBI case was registered on the allegation that Verma took huge amount of money to get a Swiss defence company out of government's blacklist.
The I-T department, according to sources, has begun a probe to detect alleged kickbacks being paid in the case and it has begun a preliminary investigation into some of the overseas accounts of Verma and his associates.
The I-T department is also reportedly in possession of classified data on Swiss and other accounts belonging to Verma and others known to him.
Sources claimed the teams have collected some crucial information and documents.