Obtain a bachelor's degree in the field in which you intend to serve as a forensic investigator. Many detectives start their careers as police officers, but forensic science work requires more extensive education than what's required of policemen and detectives. Forensic investigative work and certification can be obtained in various fields like accounting, nursing, computer investigation, social work, medical investigation, consulting and counseling. The American College of Forensic Examiners International (ACFEI) even offers a certification program for physicians.
Obtain the necessary experience required by your certification program. For instance, The International Society of Forensic Computer Examiners requires that you have 18 months of verifiable experience in conducting digital investigations. The ACFEI requires that you have a minimum of three years of experience if you plan to be certified as a forensic nurse. Carefully read all the requirements for the field in which you're seeking certification and ensure you've met them before you apply.
Apply for certification training through an organization like the ACFEI or the International Society of Forensic Computer Examiners. The latter organization allows you to submit your application online, while the former provides downloadable applications that must be printed, completed and mailed. Each of these organizations offers courses that prepare you for the certification exams, but the ACFEI requires applicants in some of its programs, like nursing, to have already taken a forensics course at the post-secondary level. Each certification program has its own fees that must be paid in conjunction with your certification application.
Take and pass your certification exam. The ACFEI and the International Society of Forensic Computer Examiners both offer their certification exams online. Once you've applied, paid your fees and received approved to take the exam, you can log in and complete it.
Complete continuing education requirements to maintain your certification. Check your program guidelines through your certifying organization's website to determine how many hours of continuing education you need to complete each year or as long as your certification lasts. Don't let your certification lapse or you may find yourself having to repeat the process.