It is triggered by wiping the raider settlement and finding Mr. Bishop's notebook of payments in their possession. Bishop's holodisk is needed; it is in his bedroom safe in New Reno, which is located in the wall of the northern most room on the top floor of the Shark Club. The safe has to be disarmed with the Trapsskill, and then lock picked. Failing to disarm the trap will set it off, it will also be set off by lock picking it before disarming it, a guard will attack and turn the whole Shark Club hostile, which disrupts all quests that require talking with Mr. Bishop. Approach Joanne and hand over both pieces of evidence.