Susanna is Michael Cordero’s new partner at the Miami Police Department who comes across as a very cunning and knowledgeable Detective. She is skeptical of Michael’s motives and actions, but neither to the detriment of her professional nor emotional judgement of him. She is later revealed to have been investigating Cordero for Internal Affairs.
Susanna is shot by Rose, only for Rose to ‘die’ and then be revealed to have been Susanna all along. Rose claims there was never a Susanna, but it’s possible there was and Rose killed her.