Narcotic Radar just below have done incredible job, making everyone's life easier! The only thing I want to add, is info for the people like me, who are struggling to find the way to even start this mission.
How to get this mission?
1) Mission to defeat Mr. Tomassi (again), becomes available during Finnish Tango main story mission.
2) To get it, talk to Emily Pope in Board Room / Central Executive.
3) Get to Turntable / Containment.
4) Room with Mr. Tomassi is on your left, when you first enter Turntable.
5) Kill Mr. Tomassi.
6) To get achievement and skill points, talk to Emily Pope again.