After your first visit with the council, Ashley (or another companion) will take note of a salarian named Chorban bending over a keeper if you move close enough. Speak to him and he will tell you about his work and the grey area of legality it falls into. Eventually, he will give you a copy of the scanner and a scientific assignment, in which you need to scan all of the keepers in the Citadel.
If you speak to Jahleed first and acquire the Citadel: Jahleed's Fears quest, then you can find Chorban in the lower markets. You can speak to him and get the scanner from him there. You can also get the scanner from Jahleed after completing this quest.
Approach each of the keepers on the Citadel and scan them. You will receive credits and XP for each keeper scanned and a bonus after you have scanned all 21 keepers. You do not need to report back to Chorban.
Here is a list of all 21 keepers throughout the Citadel.
Note: This list uses relative compass points.
Citadel Tower Edit
- Right next to Chorban, it's the one you caught him trying to scan.
- In the bottom-left corner of the map (southwest), off a side corridor.
- To the east, past Rear Admiral Kahoku.
- Upper-left corner (Northwest) on the map, off a side corridor.
- West side, near the elevator to the Citadel Tower, right next to an Avina terminal.
- Northwest, near the Wards Access.
- Enter the Embassy Lounge, continue through a door and on to an "external" balcony.
- Again in the Embassy Lounge, to the northeast in an unnamed room containing computer terminals, human diplomats and an elcor.
- In the Embassies, the volus and elcor office beside Ambassador Udina's. This keeper may not appear if you travel to the embassies via the rapid transit system. This bug may also appear if you have visited the office prior to accepting the quest. Typically a quick save and a reload of the game prompts the keeper to re-appear. This keeper can also spawn under the room with a small portion of it antennae protruding up from the floor. It can be scanned for credit in this state but is very easy to miss.
- Southeast, by the entrance to the Consort's Chambers.
- West of the Consort's Chambers and south of the Krogan Monument.
- In the back room of the Emporium, upstairs.
- Upper Wards, behind the Med Clinic, across from the Rapid Transit terminal.
- Upper Wards, in the north-west corner of the Upper Markets between stalls (left of the expat's stall).
- Wards, on the northern wall mid-way along the Alleyway between Chora's Den and the Wards access corridor. This keeper will disappear off the map sometimes.
- Upper Wards, Flux, upstairs behind the Quasar machines.
- Lower Wards, in front of the entrance to C-Sec Academy.
- C-Sec Academy, in the C-Sec Requisitions office.
- C-Sec Academy, in the Traffic Control room.
- Alliance Docking Bay (Dock 422), at the end of the gantry the Normandy is docked with (This Keeper will not be present if the assignment "I Remember Me" is active).
- Ward Access, in a small, northern facing room on the corridor between lifts.
Keepers You Missed Edit
- Docking Bay
- Wards Access
- One of the keepers tucked away in the Citadel Tower
- Sometimes, the keeper in the elcor/volus ambassador office will disappear under the floor. The way to resolve this bug is to save and reload.
- Underneath the Med Clinic
- By the Ward's Access on the Presidium. It's not hidden, but often out of your immediate line of sight.
Note: The keeper in front of the Citadel Tower continues to let you examine it after it has been scanned the first time (with a warning from the VI not to disturb the keepers). "Examining" and "scanning" are not the same; the game is not bugged. It's designed this way and you are missing another keeper.
Note: Occasionally, the keeper in the Wards alleyway will get thrown out of the map if you use grenades in that area to rescue Tali.
Mass Effect 2 Consequences Edit
Scan most of the keepers and Chorban will e-mail a brief summary of his findings: the Keepers are programmed to 'wait for a signal', at which point they'll take some sort of actions, and that it is about time for that signal to arrive. Chorban states that this has happened repeatedly in the past, likening it to looking at the rings on a tree. Unfortunately, he has been unable to find anyone willing to take those findings seriously. The e-mail will be received once you've advanced enough through Mass Effect 2.
Abandoning the assignment is possible through dialogue with the scientist that originates it, and the reward for doing so is +Paragon and +XP. However, there are no corresponding Renegade points for completing the assignment.