Marissa was the Tremere prince of Washington D.C until her assassination in 1968.
Biography
Marissa claimed the princedom of Washington after the former prince fell victim to a sudden Assamite attack. Her own clan supported her claim of course, going as far as to grant her the rank of Pontifex, despite initial concerns. Marissa used the racist tendencies among the american population following the Civil war, and managed to secure her power and hoard many magical artifacts for her own use.
Strong alliances with the Nosferatu and a vicious anti-Anarch propaganda, as well as her natural charms and victorian style leadership secured her power. Some of the kindred even dared to proclaim her as "Queen of the United States". Her gender, however, made her unpopular among the patriarchal Tremere, who sent a replacement for her (a replacement that mysteriously vanished on its way to Washington).
When the Ventrue Marcus Vitel arrived in Washington, Marissa's rule had began to crumble. She had amassed too much influence and Camarilla Elders started to worry about how much power the Prince of the capital of a global superpower could exert. They found an ally in Vitel, who betrayed Marissa to a coterie of archons and blamed her death on the Giovanni.
What was never discovered, however, it was the fact that Marissa was merely a pawn manipulated by the Lasombra methuselah Sybil, the true master of Washington area, and secret sire of Marcus Vitel.
References
D.C. by Night, p. 19