I would suggest that you post this in the beginners and help section of this forum, you might see someone that can give you the kind of answer you needs.
It’s not everything you take to the general board, OP made this topic in the perfect board because only Nigerians truly understand how the legal system in the country works and the best way to go about these kinds of issues.
First of all, there is no way to recover stolen coins unless you are able to get the person that stole them and in this case your boss can’t prove beyond a reasonable doubt that his neighbor stole his coins. You confirmed with your story that your boss doesn’t know much about crypto so what are the odds that he might have clicked on some malware on his device or was hacked?