Who is Isabella Marqueza from Black Friday and what is their importance?

Marqueza is the Brazillian woman "kidnapped" by David's group and held for questioning in the Green Band incident. Marqueza is believed to be responsible for several deaths, including a wealthy oil magnate, his wife and their two young children. She tells David that she has no idea what Francois Monserrat looks like, that she converses with him by message, then addresses him by name when he approaches her in a NY store.