Asking on behalf of a friend's relative to maximize anonymity. (Most details are left out to protect the identity of this person, and I was also not given much detail to begin with.)
Dr. X is an early career scientist who had to flee his home country due to credible threat for his family. His situation is not unlike those in a witness protection program --- he and his family fled the country, settled in the US, and got new names. And they do not want to be found.
Dr. X got a new research job at University A in the US. But during the hiring process he had to reveal his old identity so that the university could verify his degree and publication records. And he was still hired as Dr. X, his old name (for a variety of additional VISA-related reasons). The university is kind enough not to list him on any publicly accessible website, and within the department, he has a nickname. So there is no problem on this end.
However, Dr. X still wants to continue publishing papers, and be active in his research community. What's the best way to publish under a different name?
Some current suggestions have their weakness:
Publish as Y, Ph.D., University A --- This will likely cause problem as anyone looking into this will not find a Dr. Y in University A.
Publish as Y, Ph.D., independent researcher --- Dr. Y's Ph.D. cannot be verified. Not acknowledging his affiliation is a tough request for a new-hire, and may cause problems with acknowledging grant funding.
Publish as Mr. Y, independent researcher --- He may not be taken seriously (by those who do not actually read his papers). And this also has the problem of not acknowledging his affiliation.
Officially change his name to Dr. Y --- This is not easy while he is still in the immigration pipeline, which can take years.
Publish as Dr. X from his old university --- This will produce too much searchable mentioning of Dr. X, and it's hard to prevent something leading to his whereabouts from being accidentally leaked. The recommendation (from those who know about this kind of thing) is apparently that Dr. X should appear to be dead on the internet.