Graff's father worked in the Drug Enforcement Administration, while his grandfather was an FBI agent. Graff followed in his father's footsteps and eventually rose to the ranks of Assistant DEA Director in Charge. Nothing else is known about his personal life. During or after 2013, he became the on-site supervisor of a joint DEA-NSA operation to dismantle the Libertad Cartel, a rising drug cartel with both an online component and an on-the-ground component. As the investigation progressed, Graff realized there was possibly a mole in the federal government operating within the Libertad Cartel and developed intense suspicions over most of his colleagues. The only coworker he trusted was Adrienne Mitchell, the DEA's Libertad intelligence specialist. He began gathering information on the Libertad's servers and saving them on a flash-drive installed on a watch, which he wore at all times.
At first, Graff is accused of being a suspect for the death of one DEA agent and two other missing agents because of the flash-drive on his wrist. Hotch meets with Graff at the DEA Cyber Headquarters to assist in the investigation. He asks him if he knows who the head of the cartel is, and Graff replies that they don't know the real name, only his alias of "George Washington". After Graff tells an agent to have Hotch find a place where he can set up, he privately tells Mitchell to find out why Hotch is really in the headquarters. Later, in Graff's office, he offers Hotch a drink, but Hotch declines it. He then asks Graff if the man in a picture on the office wall is his father, and he replies that it is. Graff then tells him about his father and his grandfather.
Graff goes on to reveal that he knows why Hotch really is involved in the case. Hotch lies, saying he believes that the headquarters has undercover access to a Hornet router. When Hotch asks if Graff has it, he replies that he doesn't. This tells him that Hotch's presence is premature. Then, Hotch gets a call from Rossi informing him that the team found evidence of a serial killer working in the El Paso area using the drug violence as a cover. Graff tells Hotch that it is a good thing that he is on the case. Later, he tells Hotch that he is having the investigation into the Libertad suspended. Then, Mitchell tells Graff that their informant was killed by a car bomb. The following night, Graff calls Hotch and tells him to come meet him. After hanging up, he steps inside his car; seconds later, he is shot and killed, and his death was unsuccessfully made to resemble a suicide.
It is revealed at the end of the episode that NSA Director Brian Cochran, "George Washington", ordered the hit on Graff because he felt the increasing pressure from the investigation.