In 2003 while investigating the murder of two drug dealers he came into contact with corrupt DEA agent James Marco who offered Lankdord $25,000 to not clear the case. Lankford was having marital and financial problems at the time and believed he would not clear the case anyway, so he accepted the bribe. This put him under Marco's control.
In 2005, he and his partner investigated the murder of Raul Levin. Lankford suspected that Mickey Haller had killed Levin, but there was no evidence to support that. Lankford had a resentment toward lawyers because he had a very negative experience with his divorce lawyer. He tended to take it out on Haller.
Lankford and Sobel searched Haller's home and one of his cars in hopes of finding the murder weapon or other evidence. All they found was the empty box for the gun. When Mary Windsor shot Haller with that same gun, Lankford and Sobel were watching the house and arrived within seconds. It became evident that the gun had been stolen from Haller and that Windsor had killed Levin. At that point Lankford seemed to acknowledge that Haller had at least paid his dues.
Lankford retired from the Glendale Police Department prior to 2012, and went to work as a District Attorney's investigator in Los Angeles. In November 2012, Marco ordered him to locate Gloria Dayton for him. After Lankford located her, Marco murdered her. When Andre La Cosse was framed for the murder, Marco ordered Lankford to request assignment to the case so he could keep on eye on it. Thus Lankford and Haller crossed paths again, and Lankford was more hostile than ever toward the lawyer. During the trial in June 2013, Lankford and Marco broke into the home of a person they believed might be called as a defense witness. Haller had equipped the house with video cameras which recorded the two men, who claimed not to know each other, engaging in an illegal activity.
The next day, 21 June 2013, Haller showed the video to Lankford who then understood that his corruption would be fully revealed. When was called as a witness he told the full truth about himself and Marco. At this point the judge cautioned Lankford about self-incrimination and had the courtroom deputy take his sidearm. However, he had a small boot gun that was not taken. When he had finished his testimony he shot and killed himself while still on the stand.