James Marco (AKA Rico or Ronald Weldon) (d. 2013 (presumably)) was an agent of the Drug Enforcement Administration stationed in Los Angeles, and a member of the Interagency Cartel Enforcement Team (ICE-T). He was also a dirty cop who was affiliated with a wing of the Sinaloa cartel. In 2003 there was a double murder of drug dealers in Glendale that Marco was somehow involved in. During the investigation he made contact with detective Lee Lankford. He sensed the Lankford was susceptible to corruption, so he offered Lankford $25,000 to not clear the case. Lankford accepted and after that was under the control of Marco.
Several years later he was ordered by his bosses in Mexico to have another member of the cartel, Hector Arrande Moya, sent to prison for life. It is not clear why they didn't simply have Moya killed. Marco had a confidential informant named Gloria Dayton who was a prostitute and drug user. He had her visit Moya and plant a gun under his mattress. He then arrested Moya for possession of cocaine, and the gun enhancement resulted in a life sentence.
Ten years later Marco was still controlling Lankford while the latter was working for the D.A.'s office. When Marco learned that Moya was pursuing a Habeas Corpus petition based on planting the gun, he realized that Dayton could end up testifying against him. He had Lankford locate Dayton, and Marco killed her. Andre La Cosse was framed for the murder. It was going according to Marco's plan until Mickey Haller and his team uncovered the links between Marco, Lankford, Dayton and Moya. Marco attempted to intimidate Haller but he was unsuccessful. He was subpoened by Haller and appeared in court on Friday, June 21, the same day that Lankford also testified. After Lankford killed himself in the courtroom, Marco disappeared. It was believed that he went to Mexico and he was probably killed there.