Who is Susanna Dayton from The Mark of the Assassin: A Novel and what is their importance?

An investigative reporter for the Washington Post, Susanna is a friend of Elizabeth Osbourne, having been a fellow classmate in law school. Susanna is investigating collusion among Elizabeth's boss, Sam Braxton, and two other powerful individuals, private businessman and defense contractor Mitchell Elliott and Paul Vandenberg, White House Chief of Staff. As Susanna got too close to the truth, Elliott had her home bugged and her movements followed. Ultimately, Susanna is murdered as an unintended consequence of one of Elliott's goons trying to steal her disks and documents.