I'd recommend some classes that help you with analytical thinking, in general. Algebra, Geometry, Logic (may only be offered in college - usually in the Philosophy dept), perhaps even a coding class. A lot of schooling teaches you to memorize. You need to learn to think and make decisions. As an example: A case I was working on for an attorney, involved a man who was fatally shot by police. As I looked at the crime scene photos, this one electronic gadget kept showing up in different places. It was never logged as evidence, never identified. It turned out it was an MP-3 player. The info we had received was that the young man was simply listening to music (and "looking" at a gun he had). The MP3 player was the music device.
You can go one of two routes: be a civilian crime scene investigator, or, become a police officer and either work up to the investigator position, or work for a department that allows its patrol officers to also do at least the preliminary crime scene investigations.
Other things to consider: Join a police explorer post, if available. Attend the Citizen's Police Academy, if available. First go into the military prior to seeking civilian employment. I don't see either youth or adult programs offered in your city or in Charlotte, so you may need to look around at other cities or check with the county. If you go to college, they may have related clubs you can join.
In college, look towards getting a criminal justice degree. They may or may not offer specializations in various areas.
Oh, and here are some non-law enforcement crime investigator positions in San Antonio. (the first 4 jobs listed), to give you an idea. San Antonio is specialized, and patrol officers don't get to do much in the way of investigations, they usually call a detective-investigator.
Pre-trial investigator in the District Attorney's Office
Victim Liasion in the DA's office
working for nonprofits - such as women's shelters
Juvenile Justice System
Attorney, either prosecutor or defense
Paralegal, works for attorneys
Crime scene investigators (can be a civilian rather than an officer, in some places)
Teacher, vocational rehab counselor, chaplain, within the prison system
The common thread: you need to be good at writing - clear, concise reports.
You should understand people - take a psychology or sociology course.
You need to have a "clean" background. Avoid drugs, going into an unreasonable amount of debt, don't hang out with the wrong people.
Most of these jobs require a 4 year degree. Some law enforcement positions require a 2 year degree. some require no degree. A state commission on law enforcement sets minimum standards for each state, BUT a department within the state can be stricter.
Some positions have fitness and vision standards as well.
You really don't need to narrow it down to exactly what it is you want to do at this point. Just start working in that direction.
Let me know if there are specific questions I can answer!