From Halopedia, the Halo wiki
Mehmep was a Covenant Unggoy. During the 9th Age of Reclamation, he landed on the human colony of Reach during the campaign there. He then had a conversation with an unnamed Unggoy, in which he brought up the extreme tension between the Sangheili and the Jiralhanae while the problem was being ignored by the Prophets. He also mentioned a Jiralhanae named Bracktanus.
His conversation was recorded by Corporal C. Errera and transmitted to ONI, who have listed the transcript as classified. His fate is unknown.