In 2004, Corbett's daughter Darci became the fourth victim of Brian Matloff, a.k.a. "The Blue Ridge Strangler". After learning of the news, he immediately went to the crime scene to confirm it himself, but he was led away by Spencer Reid, who was investigating the case with Aaron Hotchner and Derek Morgan. Corbett went on to befriend Reid during the investigation. Later on, Matloff was tracked down by the BAU, but was critically injured after falling off a high rooftop and slipped into a coma. In the following four years, Corbett and his wife divorced, presumably because Corbett was unable to move on from Darci's death.
Four years later, Matloff woke up from his coma, but suffered from focal retrograde amnesia as a result of his injuries; he is unable to remember anything about his past, not even his name. Despite this, Matloff is still put on trial. Corbett attends the first hearing and approaches Reid afterward, expressing his doubt about Matloff's amnesia being legitimate. He asks Reid if the amnesia argument would hold up in court, and Reid replies that they have a strong case against him, which relieves him. He then comments on Reid's new hairstyle and then the idea of closure. When Reid asks about his wife, Corbett tells him about their divorce, which surprises him. Corbett then goes on to say that it was okay and that everything is going to be okay now. A few days later, he is seen standing in the courthouse parking lot, watching as Matloff is taken out of a police transport van and into the building. Later, he is one of the attendants of the hearing and watches as Matloff's attorney, Lester Sterling, tries to discredit the BAU's profile of the unsub during cross-examination.
When the judge adjourns the court, Corbett storms out of the courtroom, looking upset. Noticing this, Reid catches up to him and tells him that Sterling's cross-examination wasn't as bad as it sounded. Corbett replies that he wasn't worried by it and that he had a better understanding of things. He then says that he had been seeing a therapist who helped him control his guilt and told him that there were things in life that he could not control. When Reid says it was wise advice, Corbett laments that he knows he has no say in the courtroom and says "See you later, Spencer" before leaving. He goes back to his car in the parking lot, pulls out a revolver from the glove compartment, and looks at it for a moment. The next day, he waits for Matloff to arrive at the courthouse. When he does, Corbett gets out of his car and prepares to shoot Matloff, but is stopped by Reid before he can even pull out the gun. Reid persuades him not to do it by telling him about what Darci would think if she saw him doing this, and Corbett gives him the revolver. When Corbett asks him how he knew what he was planning to do, Reid replies that he had been strangely calm yesterday and that he called him by his first name.
Corbett later attends the hearing, where he watches Nina Moore, Matloff's biological mother, testify. Through this hearing, he realizes that Matloff took Darci's watch and sent it over to the unknowing Nina as a present. Afterwards, he is not present when Matloff regains his memories and manages to escape captivity. After Hotch and Reid track Matloff down and recapture him, Reid tells Hotch about Corbett bringing the revolver to the courthouse and planning on using it as a form of closure. Reid then visits Corbett at his house, telling him that Matloff chose to switch his plea to guilty and that the jury decided on a sentence of life imprisonment without the possibility of parole. He returns Darci's necklace to him, and Corbett says it was of Darci's grandmother, who she was very close with. Reid then asks about an inscription on the back of the necklace, "Glory of the flower", and Corbett replies that it was from a poem by William Wordsworth that Darci and her grandmother liked. He attempts to recite the poem, but he is soon on the verge of tears and doesn't finish. He thanks Reid, who leaves with Hotch. A voiceover of Reid then finishes the poem as the episode's ending bookend quote.