C.I.D. Season 1 Episode 61 The Blank Letter - Part 1 1998

A diamond merchant named Vikas receives a blank letter addressed to a man called Ramesh, soon we can see Vikas in a hurry to crack his deal of 50 lakhs worth of diamonds. Later, CID receives a call that Vikas has committed suicide as no one saw anyone getting inside or outside of his house and Vikas had used his gun to kill himself. But the diamonds from his room are missing and upon further investigation it is revealed that Vikas did not die from his gun, thus proving that Vikas was murdered.