Two stealth kills in less than three minutes

In the game Assassin's Creed for the Xbox 360, in the memory block 4 one of the informers from the rich district of Damascus will give you a mission to assassinate two guards in less than three minutes.

It must be done as a stealth kill, that is, no witnesses (or at least not witnessed by guards). But the NPCs I must kill only wander on streets full of guards.

I don't get a single moment with the white icon indicating I'm unnoticed. If I try using the hidden blade while the icon is yellow, the mission fails. If I try to throw a knife from a certain distance I am imediatelly noticed.

I tried to follow this video

How do I complete this mission?

Well, when I asked this question I wasn't aware of the possibility of low profile stealth kills.

With the hidden blade equipped, move in blend mode (holding A), then press X to assassinate the target (keep holding A). You have to be very near the target, preferably behind its back.

How I completed the mission without using low profile stealth kills:

I noticed a few important things:

• Some guards will roam the city, patrolling the streets.
• Some guards will stand in a fixed position.
• If you kill the guards that have a fixed position, trigger a red alert, run away, escape, get incognito again and return, the positions ocuppied by these guards will remain empty.

So I killed the guards on the market streets, failed the mission (but didn't die), tried again, waited for the target to be near one of these empty positions, and performed the kills.