After DNA evidence linked proved that the married Randall had been having an affair with recently murdered journalist Denise Baines, Gabrielle and Darren were called by Randall and were present for a meeting with him, Horatio Caine, and Eric Delko. When confronted directly with the evidence linking Randall to Denise (a dress of hers with Randall's semen on it), Gabrielle probed Eric and had him confess that he'd briefly left the boxed evidence unattended to break up a domestic dispute; a fact that Darren used to declare the evidence inadmissible.
The investigation into Denise's murder also led back to the murder of Jimmy Ruiz, who was shot to death by nightclub owner Delonte Cassell. Delonte was another client of Darren and Gabrielle's, and was let off due to a lack of evidence. Delonte was briefly questioned by Samantha, Ryan Wolfe, and ASA Josh Avery before being stopped by the arrival of Darren and Gabrielle, with the former arguing the bullets recovered from the freshly paved alley behind Delonte's club that proved his guilt were cross-contaminated due to an unknown 45 shell casing being among the nine millimeters that were recovered. Later on, however, Delko recognized Clyde Novak (one of Darren's clients) as the man he confronted in the domestic dispute, leading to the reveal that Darren (and by extension, Gabrielle) had been employing underhanded tactics in order to help their clients avoid arrest, as they had done numerous times in the past.
Along with having former clients Clyde Novak and Beth Johnson stage a dispute in order to lure Delko into leaving evidence against Randall unattended, the villainous lawyers also had Josh (who was dating Samantha) working as a mole for them and had him insert the 45 shell casing into the recovered bullets in order to sabotage the case against Delonte. It was also uncovered that Darren paid hitwoman Ashira Botnick to kill Denise in order to silence her, as she had been using her affair with Randall to uncover his corrupt deeds and was close to exposing him. Just as Horatio was about to convince Randall to testify against Darren, he was called back to the station and met with Darren and Gabrielle, with Darren claiming his colleague had something to tell them. It was then that Gabrielle confessed to being fully responsible for tampering with the case against Randall and orchestrating Denise's murder, claiming she did so to protect her client. As Darren told Gabrielle he would make sure she had a good attorney, Horatio and Natalia Boa Vista attempted to convince her not to be Darren's scapegoat, believing Gabrielle was being blackmailed by her colleague into making her false confession. Despite that, however, Gabrielle continued to stand by her claims and asked to make her official statement, leading to her off-screen arrest.