Marvin "Marv" Peterson was a counterintelligence agent for D.O.D. and Jesse Porter's former handler.
Marv recruited Jesse into the counterintelligence wing of the D.O.D. He had worked counterintelligence for 27 years.
After his agent, Jesse, got burned for being accused of stealing sensitive intelligence, Marv had an unwelcome reunion with him at the next International Intelligence Conference at the Eden Rock Hotel. Jesse came to Marv to extract information about a bank heist that was meant to steal Simon Escher's Holy Bible, which contained information on the people responsible for burning Michael Westen along with many other operatives. It was Marv's information that led to the takedown of Drake Technologies and its CEO, John Barrett.
Some time later, Jesse approached Marv again for $5 million to buy an entry into an auction for the Bible after it was heisted by former Drake Technologies employee Justin Walsh. Marv secured the required funds to help Jesse get a seat at the auction. His involvement with Jesse continued with the spy who burned him: Michael Westen. To validate the information and story about the list and Michael's actions in Miami, he held interrogation sessions so that Michael can gain his trust and deliver the list safely. After validating Michael's story, Marv finally agreed to arrange for Homeland Security to transport the list out of Miami.
Unfortunately, Tyler Brennen intercepted him and threatened his wife's life if he did not give him the list. Brennen forced Marv to go to the meeting as planned and Brennen's men would pose as Homeland Security agents. At the meeting, after Michael and Jesse delivered the list, Brennen ordered his men to execute Marv before exiting.