In the 21-page note, Nath wrote he had been forced to take the extreme step under pressure from contractors who had been denied projects despite paying several lakhs of rupees.
Nath wrote he had collected the money from contractors in Sonitpur and Udalguri districts and had given it to Enamul Haque Laskar, Congress MLA from Sonai assembly constituency in southern Assam. Haque was then the officer on special duty in the irrigation department.
Haque rubbished the content of the suicide note, denying any involvement with whatever Nath did. The police said action could not be taken against Haque on the basis of the suicide note.
On Wednesday, the Gauhati high court admitted a writ petition seeking CBI probe into the alleged scam. The court asked the police and CID to file the status report before December 19.
Petitioner RP Sarmah, an advocate, cited Nath's suicide note for probing MLA Laskar's role in his death believed to be associated with the scam.
Assam Pradesh Congress Committee spokesman Mehdi Alam Bora said the party was in favour of a formal enquiry into the matter.
"The party will not interfere in any legal proceedings brought against Haque in connection with the case. We are also contemplating an internal inquiry into the allegations," he said.