I'd be grateful if you could help me with this...Imagine we're in a party and we find out a friend I've already drifted apart, now if I try to look at other directions to avoid him, I'm Blanking him,...What if I give him a swift glance but just pretend I haven't seen him at all? Can I say I saw through him? (In the former example I didn't see him, 'cos I did my best not to do so, but in the latter one I just caught a glimpse of him...) Ta!
You can say "I looked through him" for the meaning you want. "Saw" suggests something about the object of your gaze or what you have observed, as Searching explained.