Thadeous Oakley is PR specialist. Thanks to him, Shai-Gen organization is perceived positively by the residents of Pacific City. It also increases the amount of new recruits. Eliminating Oakley will make people see through gang intentions.
The seat of this boss is a giant dome on the north-east territory of Shai-Gen. Officially, it's an expo center. In real, it's a cover for brainwashing done by Oakley and his co-workers. You will get inside using a tunnel from the west.
The dome is surrounded by the water. You can easily see a glass tunnel leading on the shore. Its entrance is near, behind the big Expo Center sign. Go inside. Act normally so the guards won't be suspicious and leave you alone. Get to the exposition room - there's a car show at the moment.
By our calculations, the best way is to jump onto terrace around the dome. Run along it and eliminate all opponents you see. Once you reach the building, head to the smaller dome in the middle (check the picture below). Inside you'll find stairs. Go up and you'll get to the Oakley hideout.
Before you deal with him, kill his bodyguards. In case of energy problems, you can hide in one of descents to lower floor, wait a little and come back healthy and strong again.
You will find Oakley on a little platform above. He will be protected from shooting by bulletproofs panels. That's why jump up and throw few grenades inside (check the picture below). It should eliminate the guards. Now you just need to finish off the boss.
To get outside, retreat to the big dome and blow up the door using rocket launcher. Go through and jump on the roof of glass tunnel - the one you came here. After a few second you'll be on the shore again.