|Original Airdate||January 8, 2007|
|Previous Episode: Backstabbers|
|Next Episode: Throwing Heat|
Internal Affairs is the twelfth episode of season 5 of CSI: Miami.
Nick is murdered in his condo and Natalia is arrested for the crime when evidence at the scene suggests she killed him, but Horatio tries to clear her name. The evidence also reveals that Delko and Nick fought earlier in the day. In another case, a wealthy single man is found dead in his mansion with a granite-topped bookshelf on top of him. The investigation reveals the victim was seeing a therapist who suddenly dropped him as a patient. It is suddenly discovered, that the two cases are related.
Natalia Boa Vista is arrested for the murder of her ex-husband, Nick Townsend, by Jake Berkeley, and the episode flashes back to the events leading up to Nick's death. The CSIs are called to the house of Benjamin Rhodes, who lies dead in the middle of his living room. Nick, still on the clean up crew, arrives early and makes sure Natalia knows he has a lunch date. The CSIs trace prints at the house to Jeff Murdoch, an AV specialist, but he claims he was in the house to sell Ben a new system. A blood smear on Ben's pants leads them to his therapist, Lauren Sloane. Ben had been making calls to the psychiatric board and the CSIs suggest he might have been reporting wrong-doing on her part, but she insists she simply dropped him as a client and her blood got on his pants when he broke a vase in her office after flying into a rage. Alexx shows Horatio that Ben was killed by a projectile--a blank fired at close range into his chest.
While Ryan goes back to the scene to retrieve the projectile, Delko answers a page: Nick Townsend has been found dead in his apartment. Horatio insists the investigation is handled carefully, calling in the dayshift CSIs and putting Jake Berkeley on as the lead detective. When DNA in Nick's bed comes up as Natalia's, Jake has her arrested, but she maintains her innocence. She and Nick were still intimate, and she had been spying on him from outside his window, but that was it. Maxine Valera comes forward with a startling confession: she admits to killing Nick. Valera was Nick's lunch date, but she tells Horatio and Jake that when he got rough with her she pushed him off and he fell. Jake wonders if Natalia and Valera planned and executed the murder together, a charge they deny.
A bite on Nick's hand lead the CSIs to Phillip Craven, a fellow crime scene cleaner. He denies killing Nick, but admits he got into an altercation with him after he discovered Nick was stealing valuables from crime scenes. The paper wadding from the blank that killed Ben Rhodes is traced back to a purchase of blanks made by Jeff Murdoch, but an earring found at Nick's apartment--lifted from Ben's house--proves to be the key: DNA on it links it to Lauren Sloane, who is in fact Jeff's wife. Lauren admits she and Ben were having an affair, but when she went to his house to end it, he refused to listen. She shot him with the blank, thinking she would scare him, not kill him. Afterwards, she admitted her husband what she'd done, and he went back to Ben's house to get her earrings, which she'd left behind. When he overheard Phillip and Nick fighting over Nick's thefts, he followed Nick and fought with him over the earrings. When the fight got physical, Jeff hit Nick with one of his tools and the blow killed him. Natalia and Valera are released, and Horatio consoles Natalia while she cleans out Nick's locker.
- David Caruso as Horatio Caine
- Emily Procter as Calleigh Duquesne
- Adam Rodríguez as Eric Delko
- Khandi Alexander as Alexx Woods
- Jonathan Togo as Ryan Wolfe
- Rex Linn as Frank Tripp
- Eva LaRue as Natalia Boa Vista