This side mission becomes active during your 2nd visit to Detroit (augmentation riots).
Please note, this mission is a tad tricky to initiate. In order to activate it you need to do the following:
1.) Once you get back from the FEMA facility, you need to talk with Prichard BEFORE speaking with Sarif.
2.) You need to obtain this trophy during your conversation with Sarif
3.) After you get Sarif to spill his beans, you need to go to your personal computer (Security Office) and read the emails he sent over.
After all that is done you will briefly speak with Prichard again. Then just continue on with the game (go to Hengsha, then Picus Communications).
Upon your return to Detroit, Prichard will contact you as you make your way to the first primary objective. He will go on about Taggert and his aide, and then, at the tail end of that discussion this side mission will be initiated.
Complete the objectives, and VIOLA! Trophy obtained.
If you have any further questions, or if anything is unclear, please leave a comment below.