After you reach the docks you will face this boss fight. The Infiltrator is like Arnold from the movies, he is a humanoid robot that shows more robot as he is damaged. The WT suggests a lengthy fight but if you use an upgraded Skynet Plasma R95 (mine did 134 damage) to quickly take him out. Having lots of heals, using cover, getting ammo boxes and 2000+ red plasma cells will end the fight as quick as possible. Aim for the head for critical hits. It is good advice to shoot him while he shoots at your allies.
He will run through a wall at 3/4 health. CHECKPOINT. He will retreat at nearly 1/2 health. move quickly or he will launch a propane tank at you and destroy you. Just run straight to the ammo box and you should be safe. Slightly below half health he will retreat, you get a cutscene while chasing him and get separated from your crew. When you find him again he will hide behind a fire which kind of blinds you, especially if you have the gamma cranked up. He will start chucking grenades at you too, so watch out. At this point I waited behind a truck and just ran in a circle getting head shots. Took 1 minute and he dropped like a rock.