جَاءَنِي الْقَاضِي — nominative subject, estimated ḍamma.
رَأَيْتُ الْقَاضِيَ — accusative object, visible fatḥa.
مَرَرْتُ بِالْقَاضِي — genitive noun, estimated kasra.
Takeaway: It is the same noun with three grammatical functions. Only the accusative shows the case vowel on its final yāʾ.