JD law to become an FBI,CIA, DEA?

It's good you're looking ahead--but you don't need to make all of these decisions immediately. Study human and computer stuff you're interested in, likewise in college. You don't have to have any specific major to get into law school, and there is no way to predict exactly what the agencies you mention will be looking for 10 years from now when you apply--but it is safe to say it will help to have language and computer skills.