It was only after he was informed by the FBI agents that Rana has been arrested on terror related charge that Headley agreed to respond to questions about Pakistani Canadian Rana, Headley informed a Chicago court during a recently concluded Rana trial.
"I did not want them to be affected by my case," the 50-year-old Pakistani American told the court when asked by the government attorney when he testified before the jury during the Rana trial.
"Why not?" the Lashkar-e-Taiba (LeT) operative was asked.
"I''m close to them. I didn't want to," Headley said.
"Besides your wife, who's the closest friend that you have in the world?" he was asked.
"Dr Rana," Headley said.
Headley said "Yes, I did" when the government attorney asked if he came to learn that Rana had been arrested.
And after Rana was arrested by the FBI on terror related charges, Headley said, he had conversation with the government about it.
After the conversation, the US attorney told Headley that if he was to cooperate it "would have to be complete," and he could not refuse to talk about any individual.
"So I decided to comply with that," he said.
The Mumbai terror accused also told the court that he initially lied about Rana to the FBI investigators, but later on provided information about him.