Luck of the Irish/Walkthrough
Head over to the building on Joliet Street. Head up the stairs and collect the Sniper Rifle from the corner you exit in. Go around the escape and step into the yellow marker. The game then gives a tutorial about how to use a sniper. Packie arrives with the "stuff." While he is doing that, aim down the sights and wait for the deal to botch, and the dealers to begin to shoot at Patrick and his Unnamed Associate .
Madly snipe all of the men and some more pour in. Zoom in with the sniper rifle and take out all of the attackers. Take your time with each shot and deal with one person at a time. Don't worry much about your health, as they won't even notice you. One of the attackers gets in a tussle with Patrick, so snipe him, and then three more attackers will arrive. Once you have taken out the three attackers, the last attacker will attempt to escape in the van. Snipe him through the windshield to complete the mission. Afterwards, Niko calls Elizabeta to let her know that Patrick is safe.