By 2558, Sekibo had completed years of diplomatic work for peace between the UEG and the Sangheili on Biko. He scheduled a peace conference between UEG senators and the Sangheili but one week before the conference was supposed to take place Sekibo found a serious security threat and asked the UEG for help, to which they declined. Sekibo went through with the peace talks anyway.
An extremist rebel organization known as Sapien Sunrise managed to infiltrate the conference and disguise as members of the UEG, one even disguised himself as Sekibo's bodyguard. Their plan was to assassinate Sekibo and other human and Sangheili delegates and blame it on the Sangheili. Their plan failed when SPARTAN-II John-117 infiltrated the embassy and killed the terrorists. He then escorted Sekibo and a few of the Sangheili away.
Sekibo's body was found laying in a field somewhere outside the city, he is presumed to have died from wounds inflicted by the firefight that went on in the embassy.