October last year, was born to an American mother and a Pakistani father and grew up in Pakistan till his parents divorced.
"It could not have been more different between the two worlds. In one world, where he wants to be Pakistani, he was considered to be an American. With Americans, he was being seen as a Muslim. So he had to get used to a duality of life," Headley's maternal uncle William Headley told NDTV.
He said Headley, whose original name was Dawood Gilani, came to the US from Pakistan at the age of 16 to reunite with his mother, who had just found a man, her future husband, and ended up ignoring him.
"...and it was terrible for him. He ended up living on top of a bar. And there are not many devout Muslims who have to live in a bar. I think it was confusing for him. The cultures are so different," William said.
He said Headley is a harlequin -- a person having different coloured eyes. "Usually one is blemished, but he has a clear blue and a clear brown eye. So if you look at him, he is split down the middle."
Headley was "almost like two different people," William said. "They say East is East and West is West and never the twain will meet... but they met in Dawood. I have seen all of this. I would have him split down the middle... and he would be David Armani and Dawood Gilani."
"David Headley had short slicked-back hair, very clean-shaven, he'd be wearing an Armani suit...looking really sharp. And he would have a bottle of Dom Perignon under his arm. The other side would be Dawood Gilani... and would be in native dress, and would have the long fundamentalist beard and would have the Quran under his arm."
He changed his name to David Headley so he could come back and forth, William said. "He could pose as either one, and be completely believable, because it is partly true."
But, he said, Headley had never done anything against the US, for which he worked as an undercover agent in the past.
Asked if he was in touch with Headley, he told the channel, "Yes, through letters."
"He is in maximum security so (he) is only allowed letters. Both my letters to him and his letters to me are read by the authorities."
To a question whether Headley mentions his case, charges against him and India, William replied: "He only said that we should expect many surprises."