Missing person poster
From Halopedia, the Halo wiki
The poster is in the same spot in both The Storm and Floodgate (as they take place in the same area), but the instructions for getting to it differ between each. The poster is, however, more difficult to read in Floodgate, due to the level's lack of light.
Near the end of the level, as you enter the last outdoor area leading to the Anti-Aircraft Battery, make your way through the crowd of Brutes and Grunts until you get to the Prophet of Truth's hologram projector. At this point, turn left. You should see a "hallway", a narrow corridor with walls on both sides -- walls that have openings in them. The poster can be found lying on the floor in one of the openings on the left side.
As you make your way down the hill and back into the factory complex, a Marine should radio in, "All squads, report!". At this point, go straight until you reach the corner, where flames can be seen behind a Fence Wall. Here, turn left. As with before, you should see a narrow "hallway". The poster is lying on the floor in one of the openings along the right wall, past the dead Brute Chieftain with a Gravity Hammer.
The text of the poster has been reproduced here. Comments are in italics.
MISSING File #: 1-17343 Name: Jason Jones Sex: Male Height: 5'9" Weight: 160 lbs Hair: Dark brown Eyes: Dark brown Last seen in Voi and N. Mombasa wearing khaki shorts and a dark baseball cap. MISSING SINCE: November 9, 2552 This is the second notice issued for Jason Jones whom was last seen in Voi and the New Mombasa badlands after the Covenant invasion in 2552. If you have any information on this individual please contact the local authorities or call any of the numbers below to file new information on this case. Voi Greater Outlands Police Bureau (4679)7994-343 Western African Committee on Missing Persons [ed. note: The last line of the poster is illegible.]