To become a Private Investigator in the country of Vietnam does not require a specialized license. Furthermore, the country of Vietnam does not issue PI licenses. After learning how to perform investigations, you can simply work as a Private Investigator in Vietnam. It is recommended that you first learn how to perform investigations relevant to the PI industry. The fact that Vietnam does not have licensed Private Investigators does not mean that the quality of investigations is less in Vietnam than in other countries or states. In fact, due to poor state industry standards, having a PI license does not make you a qualified Investigator. The poor industry standard come from the non-relevant experience most, if not all, places require of you to become a licensed Private Investigator. This non-relevant experience can be education degrees and non-PI investigative experience.
An industry standard flaw most jurisdictions have is regulations regarding law enforcement experience. Most jurisdictions allow you to obtain a PI license if you have law enforcement experience. Some jurisdictions also accept non-PI investigative experience to obtain a PI license. The problem with jurisdictions requiring previous investigative experience is that there is no such thing as equivalent Private Investigator experience. Sure, a career in law enforcement will gain you some transferable skills to bring to the PI world. However, an investigative career outside of PI work will not provide you the skill-set to perform what we do the most: single person surveillance for insurance fraud investigations. Furthermore, PIs typically obtain all evidence via quality and litigious video. This is uncommon for most other investigative careers. Being a police officer will not make you a good PI the same way being a PI will not make you a good police officer.
Some jurisdictions also require you to take an approved PI licensing course. However, these courses typically focus on what laws you need to be aware of. This is of course useful, but new Private Investigators still need to learn how to perform investigations. The required courses do not focus on what we do most: single person mobile surveillance. Often, these courses do not not even mention single person mobile surveillance. If you are becoming a PI, you need at least 100 hours of surveillance experience to be able to perform safely and meet client's high standards.
Another requirement issue is the acceptance of post-secondary degrees. These degrees that are accepted for PI licensing are typically in the criminal justice field. However, some jurisdictions accept any post-secondary degree. The issue is, having an educational degree will offer almost no help to you in the Private Investigation industry.