How do you get collectible locations from commander?

[Floymin]

Can you only get them if you do a silent kill?

[Floymin]

I wasn't talking about the items, I was talking about the map. Didn't you ever do a silent kill on a commander and then check your map?

[KHARNIFEX]

You get maps by finding them laying around or in frames, like picture frames, in the levels. If you press M, and you see exclamation marks or question marks, it's either a map, collectible, or enigma code.

[Floymin]

I can't believe I am being so confusing! I found out on other forums, anyway!
The question marks for the collectible locations DO only show on the map by stealth-killing a commander! They won't show up if you just gun them down.