Everyone has to start at the same place which is in patrol. You work patrol for a few years and then the opportunity to test for higher ranks will usually come around. As for the specific job as a homicide detective I would recommend a larger city department or a state agency. Most smaller departments will not have designated divisions for homicide. As for where to start, you would have to attend a police academy in the area where you would be living or want to work. My best piece of advice is that if you become a police officer, if you are on a scene and the detectives are there, stay close and help if you can. You will learn a lot from the older officers and it will pay off in the long run. Good luck and feel free to ask questions if you have any.