CB-CID wing of Tamil Nadu police made the announcement in connection with the murder of KN Ramajeyam, brother of DMK strongman from Tiruchirappally and former Minister KN Nehru, in 2012.
The Crime Branch wing also offered Rs two lakh reward on information relating to a heist of Rs 5.78 crore worth soiled currencies from an inter-city train service last year.
Referring to the Ramajeyam case, police said "a cash reward of Rs 2 lakh for the above case would be given to the person providing useful information that would lead to the detection of the case."
Regarding the heist, police announced a reward of Rs two lakh to those providing "useful information that would lead to the detection of the case."
Unidentified assailants had made a hole on the roof of a Salem-Chennai train and done away with the cash belonging to the Reserve Bank of India.
Police gave various contact numbers for sharing information on the two cases and assured that the identity of persons sharing information would not be revealed.