Joseph Mbarga appears in The Survivor in the Soap.
He was a general and warlord in Africa who is described as a monster. Mbarga was responsible for recruiting thousands of child soldiers and an untold number of deaths. Mbarga disappeared after the war and was still wanted for war crimes.
He eventually ended up in America where he got a job as the janitor named "Tony Dennis" at the building one of his former child soldiers, Symchay Conteh, was living in. After Symchay threatened to expose him, Wilford Hamilton, Mbarga's lawyer murdered him.
With the help of Brima Chalobah, Doctor Temperance Brennan and FBI agent Seeley Booth identified Mbarga through a picture in Kimberly Singer's art gallery, the picture that had so upset Symchay in the first place.
Mbarga was subsequently arrested with Booth claiming that Mbarga's fingerprints and DNA confirming his identity. However, he claims to have "heard" that he was never fingerprinted and that all DNA evidence was destroyed in the war. Mbarga continued to insist that he was innocent despite Booth warning that if he didn't confess to murder in the United States, he would be deported to the Hague to face seventeen counts of crimes against humanity. Mbarga demanded that Booth either release him or call him a lawyer and Booth left him alone.
After the interrogation, Booth's real motivation in questioning Mbarga was revealed: it allowed Angela Montenegro to compare Mbarga's interrogation video against a pirate radio broadcast Mbarga made twelve years before. The voiceprints from the two recordings proved to be a perfect match, confirming Mbarga's identity. Booth had never cared what Mbarga had to say as long as he said something they could use to compare his voice with. The killer was eventually proven to be Wilford Hamilton, but Booth assured Brennan that he had Mbarga on at least a thousand other murders.
Though he was proven to be innocent of Symchay's murder in the United States, he was still deported to the Hague to face trial for his war crimes and was presumably ultimately executed for the things that he had done.