When did Lord Vader find out Luke was his son?

Vader is suspicious that Obi-Wan was hiding something, but he doesn't yet realize that Luke is his son (he doesn't learn his name in this scene). ... I sense your anger. Great anger. Have you something to say? Some proud, defiant words? Or are you wise enough to know your place? (beat). read more

In Issue #2, after taking Luke's lightsaber, Vader takes a closer look at it and realizes it used to be his own. Vader is suspicious that Obi-Wan was hiding something, but he doesn't yet realize that Luke is his son (he doesn't learn his name in this scene). read more