A good Investigator needs to know more than a little law. Many cases I work on involve subjects who legally change their names, often in contravention of the relevant law. For example, Michigan law disallows a name change if you have been convicted of a felony or have been committed to a mental institution. However, The con-man known as “Prince” von Habsburg-Lothringer (really Josef Meyers, a former Detroit mental patient) was able to change his name.
Many jurisdictions have laws that say you can’t change your name to avoid debts or prosecution, and if your are a convicted felon or on parole or probation. I have found all of these types changing their names. Nobody really checks the background of people who change their names in many jurisdictions. You can use this to your favour in some circumstances as the local authorities don’t want the public to know how lax they are in this regard. A complaint to the right bureaucrat often leads to interesting and highly useful assistance.