Megan Hendley is an agent for the CIA. She was a colleague and wife of a CIA agent, who became obsessed with a plot from a Russian arms dealer to retrieve nuclear warheads placed in the U.S during an operation in the 70's. She found out about her collegue and husband's death and when NCIS Agents Sam Hanna and G. Callen came to talk to her she was under the impression that they were going to kill her and was hostile to them until they were shown to be NCIS Agents.
She then had them interview her on her colleague/husband and she gave them all the information she knew.