Sources in CBI, which had conducted the investigation for 17 months, said the agency recently filed the report in a special court in Chennai saying the post-mortem examination report has concluded that it was a suicide.
They said the forensic examination of the suicide note also said it was of Batcha himself.
Batcha was found hanging in his house at Teynampet in south Chennai on March 16 by his wife and driver, nearly a month after Raja's arrest in the 2G case.
The agency had used the services of forensic experts from AIIMS to detect if Batcha was killed but even after detailed examination, sleuths have not found anything which can substantiate the murder hypothesis, CBI sources said.
CBI had, for cross-checking, roped in a team of doctors from AIIMS to examine the viscera and post mortem details of Batcha to ascertain if there was any "foul play" in his death.