Golding's use of dialogue absolutely reveals Ralph's involvement in Simon's death. Ralph brings up the topic first to Piggy who would like to avoid speaking of what happened altogether. Piggy is of the mindset that if perhaps he and Ralph ignore what happened or pretend that they were not involved then it makes the reality less of a threat, that they can pretend it never happened.
Ralph insists on speaking about what happened the night before, claiming "That was Simon...That was murder" (156). Golding characterizes Ralph's voice as "low and stricken," and has Ralph "cradling the conch," the object that represents law and order on the island. Ralph's actions suggest his guilt and inability to deal with the enormity of his and the group's actions that night. He reminds Piggy, "Don't you understand, Piggy? The things we did--" (157).
Samneric's dialogue also reveals their reluctance to accept their own involvement in what happened to Simon.
"We were very tired," repeated Sam, "so we left early. Was it a good--"
The air was heavy with unspoken knowledge. Sam twisted and the obscene word shot out of him. "--dance?"
Memory of the dance that none of them had attended shook all four boys convulsively" (158).
The twins' avoidance of the topic confirms their own participation; for if they had no idea about what had happened, Samneric would not have acted so awkwardly about the topic.