A degree in Criminal Justice is usually the standard that police agencies requiring a degree look for, however I've found that the best education for something like a "Special Victims Detective" is the training and education you can get through your agency. Once you're a member of a police department look into the training schedules in your own agency and other police academies pertaining to "sex crimes". Express an interest to your department in that type of assignment. There are also many informative writings, articles, journals and books as well as seminars to educate you in this area. The best education though is 'OJT', on the job training and picking the brains of experienced detectives.
This professional recommends the following next steps:
- Research the agencies your interested in working in, see what their requirements are for becoming a Sex Crimes Detective. Read articles, literature, attend a seminar or two regarding sex crimes, educate yourself a little on the topic, if you are a college student, as a project go interview a sex crime detective in your area.
- Apply for a position/ take a test for a police agency. Study hard.
- Go for it.