Joey Quinn

Joseph Quinn is a detective who transferred to the Homicide division after being in Narcotics before Season 3. Quinn takes a liking to Debra Morgan, even giving her a C.I. to help with the Oscar Prado case. Quinn's past is unknown and even called into question, as Debra is pressured by Internal Affairs agent Yuki Amado to gather evidence against him. Quinn got the Internal Affairs case dropped, and later confessed to Debra that the real source of the Internal Affairs investigation was from the death of a former partner of his and Yuki's who had a crystal meth addiction. Quinn knew about the partner's addiction but tried to offer private help instead of informing his superiors. He is seen at Dexter's wedding, despite Debra's advice to Dexter against inviting him.
At the beginning of season 4, Quinn is infuriated when Dexter botches a case he worked on. Soon afterwards, Dexter sees Quinn stealing money from a crime scene, and Quinn attempts to buy Dexter's friendship with expensive football tickets, but Dexter gives them away to Masuka. Meanwhile, Quinn starts a relationship with Christine Hill, a seductive reporter who takes advantage of his access to police information. After a confidential police lead appears in one of Hill's articles, Lt. LaGuerta warns Quinn to be wary of any reporter who squeezes him for confidential information over pillow talk. Nonetheless, Quinn tells Hill about numerous police reports (supposedly "off the record"), and she uses this information to expose Frank Lundy's return to Miami. Quinn breaks up with Hill after the article about Lundy, but they soon make up. Though more careful about what he says around her, Quinn still defends Christine when Dexter tells her to leave Debra alone, as Hill claims to have wanted to do a "hero piece" on Debra. All of this leads to Quinn developing a confrontational relationship with Dexter. After Hill, revealed to be Trinity's daughter, shoots herself, he is clearly distraught.
In Season 5, he strongly suspects Rita was really murdered by Dexter and not Trinity, because of subtle differences in MO and because Rita shared a kiss with the neighbor. He also believes that Dexter was the Kyle Butler that was hanging out with Arthur. He tracks down Trinity's son, hoping he can identify Dexter as Kyle, but he is stopped by the FBI and suspended by LaGuerta. Unable to continue, Quinn hires Stan Liddy to investigate Dexter. After a one-night stand with Debra, Quinn repeatedly tries to get her back into bed, eventually succeeding as the two begin to date, until Debra discovers that Quinn was suspended by LaGuerta for investigating Dexter, and not taking vacation days as he had said. Liddy begins to harass Quinn but Quinn does not wish to continue investigating Dexter because of his romantic feelings for his sister, Debra. Stan Liddy was killed by Dexter in self-defense. Quinn is the main suspect because there is blood on his shoe and numerous calls between his phone and Liddy. Dexter makes the blood evidence on Quinn's shoe go away and Quinn is once again a free man. Quinn thanks Dexter, who plays dumb and just says "For what? Just doing my job."
In Season 7, Quinn falls for Nadia, a stripper who works at a club, The Fox Hole, operated by the Ukrainian Koshka mafia. He steals evidence that would have convicted Isaak Sirko in an attempt to win Nadia's freedom from Koshka control. However, after freeing her from her strip club job, Nadia runs away to Las Vegas leaving Quinn brokenhearted. In the season finale he is seen having drinks with Angel Batista's sister.