Maria LaGuerta is a recurring antagonist on Dexter television series. She is the police Lieutenant and Captain of Miami Metro Police Department.
LaGuerta was very ambitious and politically driven. When she lost her job to Esmee Pascal, LaGuerta began sleeping with Pascal's fiancé Bertrand to get back at her. Pascal was replaced and Laguerta stopped sleeping with Bertrand out of guilt for what she had done which was why she refused to speak ill of Pascal to then-Captan Matthews.
She is very determined to maintain her position no matter the cost, such as blackmailing Captain Matthews into promoting her. She is also very manipulative, telling Matthews that she would help make the call girls case go away, but instead used Debra by having her dig information on the case that would connect back to Tom and sold him out to the board and had him forcibly put into retirement to gain his position. Even Debra commented on how that was a very low thing she did to Tom and Debra prompting her to ask "How do you sleep at night?!" to which LaGuerta replied "very nicely, knowing that from now on you will do as I say or I'll find someone who will". This shows that Maria is often more than willing to betray or use anyone to get what she wants, regardless of who she is close to.
Despite her manipulative nature, however, she often shows compassion, loyalty, and has a strong sense of justice. Laguerta was willing to bring down her former lover Miguel Prado when Dexter informed her to show he might have killed Ellen Wolf and was willing to prove that Sergeant James Doakes was not the Bay Harbor Butcher. She comforts Debra when Joey Quinn was arrested for the murder of Stan Liddy (though later released because of Dexter), telling her to "have faith" and when she was feeling bad about how Travis got away, telling her she did a good job in trying to catch him. She did admit that what she did to Matthews was wrong, but felt it had to be done despite Deb's statements of how she really did it for herself (which was true).
Laguerta has a strong bond with Dexter since she suspended Quinn for investigating Dexter for the murder of Rita Bennett. Laguerta also gets Dexter to sign papers for the official marriage between herself and Batista and trusts only him when like when she was investigating the murder of Ellen Wolf.
Laguerta first disliked Debra, but she then started to like him. Laguerta also wanted to adopt a Cuban boy, but changed her mind after locating his uncle. Laguerta is also obsessed with the Bay Harbor Butcher since believed that Doakes was innocent.
Maria was good friends with Dexter. However her obsession with the BHB ruined everything. She knew Sergeant James Doakes was on the trail the Bay Harbor Butcher and the Bay Harbor Butcher is Dexter Morgan. What they don't know is, Dexter is the good guy and he only takes out serial killers and criminals. James figured out Dexter is the Bay Harbor Butcher. He would do the world of favor to arrest him or kill him. But Lila West already killed him. But Dexter doesn't like Lila West killed an innocent person, he took her out and also to protect her. Dexter pin the Bay Harbor Butcher to Doakes. Maria for a long time, knew Doakes wasn't the bay harbor butcher and figure out it was Dexter. She even arrested him and has enough evidence to put him away. She doesn't see the big picture, that all of Dexter's victims were all criminals. She is the main reason why like any other female cop hides behind the law and the badge. That is talk for, they don't care about protecting protecting just law and order they only care about. That is what makes cops like her alone and end up dead, demoted or fired. Luckily for me, Dexter already made the switcheroo and pin the frame up to LaGuerta. Her career is over. She has only one more chance to get Dexter is by getting some close to her, is his foster sister Debra. Debra is sticking up for him. Maria followed Dexter on one of his killing sessions, but Dexter stopped her. But he didn't kill her, because of Harry Morgan rule. Debra went up their and stopped Dexter for doing something he regrets. Maria ordered Debra to kill Dexter and told her she was a good cop and a good person. Dexter gave in and told her do what you have to do. Dexter wants her to kill him, so she can keep her job and make Maria happy. Put an end of Bay Harbor Butcher. Debra chose Dexter and shot Maria. After a few episodes she quit the force and fell off the wagon. Dexter pulled her out and figure out why she chose Dexter or Maria. In her mind, she shot Dexter. I found out why, not because Dexter is family. If she shot Dexter, Maria would be bullying her whole life and the city of Miami needs the Bay Harbor Butcher to take down all the other serial killers and criminals that Miami P.D. can't touch.