Who should I write a letter to in India for security protection?

I have been threatened by one person in Bangalore that I will be harmed when ever I come to Bangalore. He has some Goonda contacts and I am scared due to this threat to my life. I am of Indian origin but holding U. S. passport. I was informed by a friend that if I write to Ministry of External Affairs in Delhi and to different respective Chief Secretaries of concerned departments in India then that person who has threatened me will be contacted by the local police and will be given a strict warning. If this is true can anyone let me know who should I write this kind of letter and who should I CC: this letter. Your help will be greatly appreciated.