Who is Tibbets from Canyons and what is their importance?

Tibbets is Mr. Homesley's Vietnam buddy and a pathologist in El Paso. Tibbets is able to tell Brennan that the skull is that of a boy around the age of fourteen, that it is more than likely an Apache boy, and that the skull died of a close range gunshot wound, but not a suicide. It is because of this information from Tibbets that Brennan is able to narrow his search and find information on the death of Coyote Runs.