Does the adopted son inherit the deceased's entire estate, thereby disinheriting the sister's daughter, and who bears the sin?

The deceased man who left behind a niece and an adopted son—neither of them are heirs. The adopted son is not the biological son of the deceased and cannot be attributed to him. As for the niece, she is among the 'dhawu al-arham' (relatives by blood) who inherit only in the absence of a legal heir from the 'ashab al-furud' (sharers) or 'asabat' (agnates).