The agency was planning to question 24-year-old K Prabhakaran, who had claimed in a press conference on May 17 that he had killed Batcha in 2011 and named a senior IPS officer and a relative of Batcha as partners in crime.
Prabhakaran had claimed Batcha was murdered after he gave CBI "vital information" that went against Raja, the main accused in the 2G case.
Since his press conference, despite best efforts of CBI, Prabhakaran could not be traced.
Agency sources said local police were not cooperating in the probe and some officers have even gone to the extent of describing Prabhakaran as mentally unstable.
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The sources said his family has also claimed that they do not know the whereabouts of Prabhakaran.
Batcha was found hanging under mysterious circumstances in 2011.
He was questioned repeatedly by CBI as the agency suspected him to be the person whose company was used to route alleged bribes of 2G scam.
Batcha had left a suicide note stating that he was "embarrassed" by the raids of various enforcement agencies and the extensive media coverage. The agency had concluded that the suicide note was written by Prabhakaran himself.