Fun fact: There is a commonly understood reference in India since as long as i've known. It is that all the corrupt businessmen and politicians stash their money in 'Swiss banks' and if this money could be repatriated a lot of Indian problems will be solved. I know this is exaggerated but this is what even the most average of Indian knows and the country does not have the leverage (at least so far till CRS) to do anything about historical wrongdoings.

Also check the relationship between Mauritius and Africa/India for another example of such a relationship. It is funny though how even in today's world the corrupt from developing countries still manage to move the money around so easily, it happens only because you have the ability to grease the right palms.

Forget about the island countries, i do not think even developed countries like UK (Russian money) or Canada (Vancouver real estate) cooperate enough if the person gets citizenship and is accused in a different country. I know because there is at least one documented case where the proceeds of a large scam in India were funneled to Vancouver real estate, how something like this is possible is beyond my understanding.