TT #311 · Parshas Tazria · Aliyah 7 · Passuk 59
English: This is the law of the lesion of tzaraas in a garment of wool or linen, in warp or woof, or in any leather article, to declare it clean or impure.
Chabad.org — Chumash, English translation + Rashi for Vayikra 13:59
Torah Temimah cites Sifra (Toras Kohanim) for the ordinary rule that the same priest handles both rulings, with succession if he dies.
Sifra — Vayikra 13, Midrash Sefer
English: The priest who declares the article pure is also the one who can declare it impure; if he dies, another priest examines it.
Textual derivation
The priest who examines and declares the article pure is ordinarily the one who later declares it impure if the condition requires that ruling. If he dies before then, another priest may examine it.