From Divine Omniscience and the Theology of the Septuagint, by Jan Joosten:

What our study establishes with some assurance is that the Greek translators believed God to be omniscient and let this belief influence their translation. The tendency to preserve or underline the notion of divine omniscience is found in the Pentateuch and in the other books, in literal as well as in free translation units.22 All this confirms the interest of the thematic approach.

A more difficult question is how to interpret these data in the framework of the debate on the theology of the Septuagint. A first possible explanation would be to describe the tendency identified in this paper in terms of Hellenization. Since Greek thought is supposedly more abstract, more conceptual, and more systematic than Hebrew thought, the belief in divine omniscience might be viewed as a typical Hellenistic theologoumenon, held to by the translators and consequently expressed in their Greek text. Such a theory would capture the truth only to a limited extent. A major obstacle in the way of this theory is the fact that the Hebrew Bible too clearly expresses the notion of divine omniscience. “The LORD is a God of knowledge, and by him actions are weighed”, says 1 Sam 2:3, in the Hebrew text.23 The God of Israel knows what is hidden, he knows what is in the hearts and minds of human beings, and he knows what will happen in the future – every one of these doctrines is explicitly stated in a variety of places.24 Divine omniscience is not a new idea born from Hellenistic reflexion on Israel’s theological heritage.