Which is the best organisation to work in CSI,FBI,CIA or Interpol?

I am currently an Indian national. I am 18 years old. I am interested in working for Law enforcement agencies such as the above. I would like to know what the eligibility is and how the salary,work atmosphere and training differs from organization to organization. I am doing my Bachelor's in Mechanical Engineering and plan to take my masters from the US. I am willing to emigrate to the US.