Lauren Vélez :(born November 2, 1964) is an American actress of Puerto Rican descent and the twin sister of actress Loraine Vélez.
Lieutenant LaGuerta : is a tough, determined woman in command of the Homicide division who is not above making her subordinates feel intimidated. She has a sincere dislike for Debra (which in later series has all but disappeared, even being happy to be the one to promote her to Homicide Detective at the end of Season 3). In the first season, she made no secret of her attraction to Dexter, whom she flirted with constantly, to his discomfort (which after the 1st season it has yet been mentioned or suggested and sees him more as a good friend). At the end of the first season, she is removed from command, but returns to her old job once the new Lieutenant proves to be unstable. When her friend and former partner James Doakes becomes the prime suspect in the Bay Harbor Butcher case, she tries to clear his name. She learns from a questionable source of two Special Forces missions Doakes took part in that directly conflicted with the deaths of two Butcher victims. However, Doakes is found dead in a seemingly accidental explosion, along with the body of drug dealer Jose Garza, and the case is closed. The evidence LaGuerta finds is ignored. After his death, LaGuerta starts a memorial fund for him, asking police officers for donations, and refuses to think of her deceased friend as a serial killer. As she recovers from the trauma of Doakes death, she leads an investigation into the murder of Oscar Prado, the brother of her ex-boyfriend Miguel Prado. She also develops a close relationship with lawyer Ellen Wolf, and is devastated when Wolf is found dead. But through the help of some personal investigation work, along with Dexter's help, she was able to discover that Miguel was the one who killed Wolf and usually confides in Dexter as he is the "only other one who knows". She becomes distraught when the Cuban community is thinking about naming a highway after Miguel and wants to find legal evidence to prove he killed Wolf, but Dexter is able to convince her that doing so would only hurt Miguel's family, the Cuban Community, and even then there is a high chance that won't prove anything and drops it.
Her characterization in the show departs significantly from that in Darkly Dreaming Dexter, in which she is a shrill, manipulative woman whose only real objective is promotion within the department. At the end of the first novel, Dexter's brother Brian kills her while Dexter looks the other way.