What is the missing number?

At the height of a political corruption trial, the prosecuting attorney attacked a witness. "Isn't it true," he bellowed, "that you accepted five thousand dollars to compromise this case?"
The witness stared out the window, as though he hadn't heard the question.
"Isn't it true that you accepted five thousand dollars to compromise this case?" the lawyer repeated.
The witness still did not respond.
Finally, the judge leaned over and said, "Sir, please answer the question."
"Oh," the startled witness said, "I thought he was talking to you."