Shmoth 2.14 "And he retorted, "Who made you a man, a prince, and a judge over us? Do you plan to slay me as you have slain the Egyptian?" Moses became frightened and said, "Indeed, the matter has become known!""
Here, hadavar הַדָּבָֽר tells us that "the matter" is "the word" - "And Moshe became frightened ... The saying is known." v.14
2.15 "Pharaoh heard this saying, and he sought to slay Moses; so Moses fled from before Pharaoh. He stayed in the land of Midian, and he sat down by a well. "
The narrative tells us first, that Moshe saved Datan from the Egyptian and then Moshe slew the Egyptian with the Ineffable Name! Verse 2.15 tells us again that "the saying" was then heard by Pharaoh who sought to slay Moshe.
When Moshe looked this way and that way, and he saw that there was no man, it implies that there were only Israelites (Hebrew slaves) present when he hid the Egyptian in the sand.
The Midrash tells us One Egyptian was task-master over ten Hebrew task-masters, who were over one hundred Hebrew slaves. Datan and Aviram were Hebrew task-masters! Not so nice of fellows. They reported to the Egyptian on a daily basis, except on the second day when Moshe found them fighting. Unaware of what they were fighting about, Moshe tries to make peace between them. Datan mockingly says to Moshe, "Who made you a man, a prince and a judge over us? Do you [literally] say to slay me as you have the Egyptian?"