Matthew Poole and continuators on Exodus 2:15

15 Now when Pharaoh heard this thing, he sought to slay Moses . But Moses fled from the face of Pharaoh, and dwelt in the land of Midian: and he sate down by a well.

Not out of zeal to punish a murderer, but to secure himself from so dangerous a person, probably supposing, that this was the man foretold to be the scourge of Egypt and the deliverer of Israel.