There are three different states that Shay can find himself in when it comes to enemies being aware of his presence and these dictate their actions towards him. The current state can be identified by the colour of the picture at the far left of Shay’s health bar. The states include:
In this state the guards will ignore Shay and will only respond or become aggressive when they observe actions that they deem illegal e.g. finding dead bodies, catching you pickpocketing etc. This state is represented by blue.
When under investigation guards suspicious of you will gain a yellow marker and will move towards you. If you let them get too close, in most instances they will become aggressive and you’ll enter open conflict. However, if you can break eye contact with the guard and hide or blend they will quickly lose interest. This state is represented by yellow.
In open conflict guards will be marked with red icons and will attack you on sight. You’ll need to kill them all or run away, break line of sight and then hide until they lose interest.