MDPD Detective Yelina Salas (Sofia Milos, seasons 1,2,3,5), a Colombian homicide detective frequently attached to CSI investigations, and the widow of Horatio's brother Raymond. She later starts a relationship with IAB Sergeant Rick Stetler, Horatio's personal nemesis. After her husband Raymond was revealed to still be alive, she left with him and their son for Brazil, where they planned to keep a low profile for Raymond's safety. She reappears in Season 5, starting with "Rio" (the season opener). Caine and Delko are in Rio to hunt down Antonio Riaz, who murdered Caine's wife (and Delko's sister) Marisol at the end of Season 4. Riaz is killed in a fight with Horatio, but not before killing Raymond Caine and enlisting Ray Jr into drug running in the shantytowns of the area. Yelina and Ray Jr wind up back in Miami, and Yelina goes into business as a private investigator (episode 522, "Burned").

Laboratory Technician Maxine Valera (Boti Ann Bliss, seasons 2-), DNA analyst. Temporarily suspended from her duties in Season 3 for technical errors, then reinstated by Season 4. Has an unfortunate habit of taking short-cuts with evidence, which caused her suspension and also brought her under suspicion when the lab was investigated by the FBI (episode 425, "One of Our Own"). She goes on a date with Natalia Boa Vista's ex-husband Nick Townsend and thinks she is his killer after he turns up murdered, though this assumption is proved to be untrue, detective investigated the case kept insisting that she and Natalia killed him despite the fact that Townsend was physically beaten to death (and with Valera and Boa Vista's lack of physical strengh made it impossible) (episode 512, "Internal Affairs")

Laboratory Technician Dan Cooper (Brendan Fehr, season 4), Audio/Visual lab tech. May or may not be related to D.B. Cooper. He believes a great deal of information can be discerned by what music a person has on his or her MP3 playlist (episode 517, "A Grizzly Murder")

Miami Dade CSI Level 3 Detective Tim "Speed" Speedle (Rory Cochrane, seasons 1-2), trace evidence and impressions expert; originally from Syracuse, New York, with a degree in biology from Columbia University, Speed was killed in the line of duty in the third season premiere, Lost Son; he had not maintained his firearm diligently, and was shot by a suspect when it misfired during a police shoot-out. The character was written out at the request of Cochrane, who wanted to pursue a career in film and reportedly disliked the long, arduous shooting schedule for CSI: Miami.

Susie Barnam Keaton (Azura Skye, Seasons 1,2,3), a meth addict who became involved in Horatio's personal life after revealing she had known his late brother Raymond. After Susie rehabs in Indiana and returns to Miami, Horatio learns that her daughter is Raymond's child (episode 208, "Big Brother"). In a later episode, her daughter Madison becomes terminally ill. Neither Horatio nor Susie are matches for a bone marrow transplant, but he convinces Yelina Salas (she assumed Madison was Horatio's daughter before Horatio told her about Ray), to have her son Ray Jr. tested. Presumably, he is and Madison is cured.

Marisol Delko Caine (née Delektorsky) (Alana de la Garza, season 4) Eric's older sister, who had Breast Cancer. Because of the painful treatments, Eric occasionally bought marijuana, to alleviate her pain and nausea. Afterwards, Eric helped to feed her when she had no appetite. Eric's friends found out when the drug dealer ruined a crime scene by droping though a skylight and then saves himself by mentioning that Eric buys drugs from him. Marisol and Horatio were married between the episodes that aired on May 8 and May 15, 2006. She was shot by a Mala Noche sniper during the May 15 episode and later died from her injury. It was later discovered that the hit was ordered by a Mala Noche boss named Antonio Riaz, who found out about Marisol's family connections through his relationship as her marijuana dealer. Not long after, Horatio and Delko follow Riaz to Brazil, and Horatio kills Riaz. Her last words were with Horatio--

Horatio: I had...I had dinner plans tonight.

Marisol: Casa Tua?

Horatio: Casa Tua.

Marisol: 8:30?

Horatio: 8:30.

Marisol: You got the good table?

Horatio: I got the good table.

Horatio: You're not planning...to...uh...You're not planning to stand me up, are you?

Marisol: Never.

At this point, Marisol is silent and holds Horatio's hand, closes her eyes, and the sound recorder behind her goes to a long electronic beep.

Nick Townsend (Rob Estes, season 5). Ex-husband to Natalia Boa Vista. Upon his release from prison, Nick re-entered Natalia's life as an employee of a crime-scene cleaning company who often worked crime scenes his ex-wife was assigned to process. Nick's treatment of Natalia following his parole consisted primarily of unwanted flirtation, which pushed Natalia into shoving him at a crime scene, an action Nick used as basis for a restraining order against her. Under the order, Natalia was forced to leave any crime scene Nick was sent to clean, which threatened her job. Nick subsequently agreed to drop the restraining order, provided Natalia treated him civilly from then on. Nick became a less-than-desirable presence on the job for both Natalia and Eric Delko, for whom Nick also took delight in causing discomfort due to Eric's prior romantic relationship with Natalia. Nick was murdered following a date with Maxine Valera, who'd shoved him to the floor in response to his unwanted advances and fled, thinking him dead. Though both Maxine and Natalia were suspected for the crime, Nick was in fact killed by a man whose wife had committed a murder Nick had worked that day. Nick had stolen an earring left at the scene by the man's wife and was bludgeoned to death when he refused to return it.