The agency is trying to establish alleged links of Rishi in the Defence establishment who helped him in procurement and supply of Tatra all terrain vehicles from BEML, sources said.
The agency has questioned a number of officials of BEML and Vectra in connection with the case.
CBI sources said they are suspecting that these officials during their tenure at Master General Ordnance Branch and the Directorate General of Quality and Assurance did not underline shortcomings in the Tatra vehicles.
They said Army officers had highlighted shortcomings in the Tatra vehicles especially alleged problems encountered during the high altitude operations on a higher gradient levels but the two branches did not question the suppliers on these issues.
Two out of three officials who are under scanner had joined Vectra Engineering while one joined Vectra Global Helicorp at senior positions post-retirement, they said.
The agency has written to the Defence Ministry seeking records of quality checks done by it and reports of field offices who were using these vehicles during the period.
CBI is also probing if better vehicles were available with Czech Republic based Tatra, why were they not preferred despite supply agreement renewed twice - in 1997 and 2003. Sources said the CBI is also trying to ascertain whether these officers received any alleged largess of Rishi during their service and whether any crucial information on procurement was passed on to Rishi.
Vectra Chairman Rishi is also Director with Tatra Sipox UK with which the BEML had signed contract for supply of all terrain vehicles.
However, CBI has found that the company was merely a minority stake holder on original equipment manufacturer Tatra. The signing of deal with Tatra Sipox UK was allegedly done in violation of defence procurement rules. Ravinder Rishi has refuted allegations against him.
CBI sources said DRDO also procured vehicles from Tatra for its missile systems which fared much better than those procured by the Army through BEML.
The agency is probing alleged irregularities in assigning supply from the Czechoslovakia-based Tatra, with which the agreement was originally signed in 1986, to the Tatra-Sipox UK owned by Rishi in 1997 showing it as Original Equipment Manufacturer and the fully-owned subsidiary of the Czech company which was against rules, they said.