Question: What former Federal Bureau of Investigation agent is the film Breach based on?
Sentence (from "Breach (film)"): The screenplay by Ray, Adam Mazer and William Rotko is based on the true story of Robert Hanssen, an FBI agent convicted of spying for the Soviet Union and later Russia for more than two decades, and Eric O'Neill, who worked as his assistant and helped bring about his downfall.
Relevant evidence: Yes