The CBI on Thursday questioned former Isro chairman G Madhavan Nair in relation to the Antrix-Devas deal after a probe led by former CVC Pratyush Sinha had found irregularities.
CBI is reported to have questioned Nair for allegedly keeping the then "UPA government in the dark" about the deal and his "conflict of interest" in the Antrix-Devas deal.
''Mr Nair was examined in connection with the allegations of corruption in the deal,'' a CBI official said.
Nair, who was chairman of Antrix's governing council when the deal was finalised, was barred from holding any government office for his alleged role in the deal.
The CBI in its FIR in the case, had named the then executive director of Antrix K R Sridhara Murthi, M G Chandrasekhar and R Vishwanathan of US-based company Forge Advisors, Devas Multimedia Private Limited and unnamed officials of Antrix, Isro and the Department of Space.
The CBI probe had revealed that the union cabinet under former PM Manmohan Singh was provided wrong information about the Antrix-Devas space band spectrum deal and the decision led to "wrongful" gain of Rs578 crore to Devas Multimedia.
Nair failed to consult ministries which were key stakeholders in the Devas deal and also failed to convene meetings at which representatives from different ministries could have voiced objections to the deal, the CAG had pointed out.
It all amounted to a criminal conspiracy entered into by government officials to favour Devas by giving it rights for delivery of videos, multimedia and information services to mobile phones using S-Band through GSAT-6 and GSAT-6A satellites and terrestrial systems in India, it was alleged.
The government had cancelled the agreement under which Antrix, ISRO's marketing arm, was to provide 70 MHz of S-band spectrum to Devas, but had to pay a heavy compensation for a broken deal.
On 16 March last year, the CBI registered a case against the Bengaluru-based Devas Multimedia, the then Antrix executive director, R Sridhara Murthi, R Vishwanathan and MG Chandrasekhar (a former Isro scientist) of Forge Advisors LLC (US) and unknown officials of the Department of Space, Isro and Antrix, accusing them of cheating, conspiracy and corruption, between 2004 and 2011, for allegedly favouring an ineligible company, which led to a wrongful gain of Rs578 crore to Devas Multimedia.
CBI said the wrongful gain - of which Vishwanathan and Chandrasekhar were also alleged beneficiaries - was made through investors from the US, Singapore, Mauritius and other countries.