"I wasn't sure if I could pull it off. I didn't have an agent looking after me or a team around me to help prepare for the part. I hadn't seen the script. And I was definitely not 'Bin Laden skinny'.
"But how does one play the global face of evil? For any actor this would have the best challenge and I loved the challenge, so there was no second thought," Ricky told in an email interview from London.
Ricky belongs to a Sikh family in Punjab but was born and brought up in Southall, West London. He graduated in Drama and Theatre studies from the University of London.
"Zero Dark Thirty" chronicles the decade-long hunt for Al Qaeda leader Osama after the September 2001 attacks and his death at the hands of the Navy SEAL Team 6 in Abbotabad, Pakistan, in May 2011.
It is being released in India Feb 15 by PVR Pictures.
When the 29-year-old auditioned for the role, he didn't know it would be for the role of Osama bin Laden, who was in his late 50s when he was killed.
"The whole story of 'Zero Dark Thirty' began last year in March. The casting director called me and told me that she had been looking for me for a week. I was asked to come the next day. When I was auditioning for the movie, I knew very little of what my role was. I mean, I just knew that it was the role of a terrorist," said Ricky.
"Later I got a call confirming my role in the movie. I was playing the world's most notorious terrorist and I was made to sign a bond that I would not leak what I was playing. I just told my mom, dad and my girlfriend because they would see me doing weird things while I prepared for the role," he added.
From seeing YouTube footage on the notorious criminal to reading books and losing weight, he did it all to look like Osama.
"To prepare myself for the task, my friend Tara, who works for the Institute of Ismaili Studies, gave me a list of books to read about Bin Laden and Al Qaeda. I bought a set of Rosetta Stone CDs to learn some basic Arabic," said the actor.
"I did not have anything more than the footage available on YouTube. The journalistic inputs definitely helped me to prepare myself for the role. I had to shed a lot of weight for the movie.
"In movies, image is everything and I was playing a very ill man. While on vacation in Jamaica, my friend Henry, a personal trainer, had me running up hills in the morning heat and eating only eggs, lean meat and fish," he added.
Though he has been in London since childhood, Ricky always enjoyed visiting his hometown in Punjab.
"I come from a Sikh family, born and raised in London. I have been to Punjab which is our hometown and it is always a pleasure going there. It's where I can trace my roots and thus feel a sense of belonging with all the exposure to the culture there," said Ricky.
Asked about future projects, Ricky said: " 'Zero Dark Thirty' is high calibre credit, as a result of which I am getting more film projects. At present I am working on Swedish thriller."