Citadel: Jahleed's Fears is obtained by speaking to Jahleed, a volus at C-Sec Academy. He thinks his business partner is trying to kill him and wants you to speak with him on his behalf. You need to find Chorban at the Markets down in the Wards.
It turns out that Jahleed stole the data from a project they were both working on. You can obtain Citadel: Scan the Keepers at this point, and after agreeing to speak with Jahleed again, this becomes Citadel: Jahleed and Chorban.
Mass Effect: Infiltrator·The Final Hours of Mass Effect 3·Galactic Codex: Essentials·Mass Effect Galaxy·Revelation·Ascension·Retribution·Redemption·Evolution
Soundtracks
Mass Effect Original Soundtrack·Mass Effect 2 Original Videogame Score [Atmospheric·Combat·Kasumi's Stolen Memory·Overlord·Lair of the Shadow Broker] ·Mass Effect 3 Original Videogame Score [Extended Cut·Citadel·Leviathan] ·Mass Effect: Andromeda - Original Soundtrack
