There is no enough and entire study on conjugated verbs deriving from the affixed structures made by /dUk/, an affix of past participle. This article aims to deal with the process of this affix from the period of the Old Turkic to Ottoman Turkish and to evaluate its position in the Old Anatolian Turkish in the consideration of new data by criticizing the studies dealing with this conjugation in the context of historical texts which appear both with and without possessive suffixes and positive and negative meanings. This article highlights as a main argument that the past participle /dUk/ consists past tense. In Turkish, perfect finite verbs can be derived from participle structures framing half sentences. The indicative moods are mainly formed in this way. Of those, the past participle affixed with /mIs/ appears in few examples in the Old Anatolian Turkish and many in Ottoman Turkish as finite verbs. The indicative mood derived from future participle affixed with /acAk/ begins to evolve just in Ottoman Turkish. It seems that the past participle affixed with /dUk/ also appeared with the form of indicative mood in the consideration of collecting the scattered data of the Old Anatolian Turkish period particularly.