Contable Harischandra, who is physically unfit said due to problem in some nerve of his brain he used to faint occasionally and could not see from his right eye.
Despite informing officers about his physical state, he was put on night duty and rigorous work was taken from him.
"I have requested the President for mercy killing", he said in his letter.
When asked Superintendent of Police, R K Chaturvedi said he has come to know about the letter but did not elaborate.