A team of officials conducted the investigation at Batcha's house, where he was found hanging on Mar 16, official sources said.
The agency started its investigation under section 174 of the CrPC which allows an investigating agency to probe cases where death has been caused by unnatural reasons.
CBI had registered a case and begun a probe into the death of Batcha, who had been under the scanner of both the agency and Enforcement Directorate for his alleged role in the multi-crore spectrum allocation scam.
The CBI's action comes after the Supreme Court's direction to the government on Monday to issue within three days a notification for handing over the investigations to the agency after it was alleged that the Centre was "sitting over" the request for the last fortnight.
38-year-old Batcha, who was questioned by CBI in connection with the 2G scam, was found dead at his home in south Chennai.
His wife had claimed he committed suicide as he was unable to cope with the pressure of the probe.
CBI and ED had conducted searches at his official and residential premises in December. He had been called for questioning four times since then.
Batcha was the Managing Director of Greenhouse Promoters, which CBI and ED suspected to be a front for Raja.
CBI in its chargesheet filed on April 2 had alleged that the money connected with the 2G scam had travelled through Batcha's company to Kalaignar TV Pvt Ltd in which Tamil Nadu Chief Minister M Karunanidhi's wife Dayaluammal was one of the owners.
The agency had said Rs 200 crore connected with 2G scam travelled from a partnership firm of Shahid Usman Balwa, an accused in the case, to Kalaignar TV Pvt Ltd.
Karunanidhi's daughter and DMK MP Kanimozhi, Dayaluammal and Sharad Kumar, Managing Director of Kalaignar TV, have 20, 60 and 20 per cent shares in the channel respectively.