This mission is given by Tam Brodie.
"Jimmy! Tam. I've been poking around for information on our friend Eddie Fu. Turns out his brother-in-law is a customs officer down at the port. That must be how they smuggle all their cut-price Asian crap into the city. That's the key to the whole Chinese operation. The way I figure it, if you could arrange for this customs guy to have a little... accident, that would be grand. You can probably find him driving to work with his two henchmen, who won't be much of a problem for you, I guess."
Follow your GPS about half a block south where you will find the customs officer in a Lassiter Series 69 marked with a large green arrow above it. You can either block his path then and there or give chase. If chased, he will eventually stop in Little Italy and a shootout will take place. Once he is dead you may take his car if you wish (as this is one of the few missions in this DLC where the Lassiter Series 69 is obtainable), then head to the safe zone to end the mission.