ALEXANDRIA, Virginia (CNN) -- Accused FBI spy Robert Hanssen pleaded not guilty Thursday to 21 charges of conspiracy and espionage, including 14 charges that could carry the death penalty.

"It’s just a question of how bad it will be." The most high-profile cases in recent history involved former FBI agent Robert Hanssen and former CIA officer Aldrich Ames, who both spied for Russia.

In February, 2001, Robert Hanssen, a senior agent with 25 years in the FBI, is arrested for spying. Jump back two months: Eric O'Neill, a computer specialist who wants to be made an agent is ...

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with his unexpected promotion and assignment to work with renowned agent Robert Hanssen (Chris Cooper). However, he soon learns the reason for his promotion is to gain Hanssen's trust and find ...