India, April 10 -- Mumbai terror attacks co-conspirator Tahawwur Rana's extradition was one of the most complex cases pursued by Indian authorities, involving multiple visits to the US, convincing the American side about due process, and ensuring the former Pakistan Army officer remained in custody when he was about to be released, officials said on Thursday.

Rana, 64, a Pakistan-born Canadian citizen, was arrested by US authorities on October 18, 2009, two weeks after his childhood friend David Coleman Headley was held for his role in planning and executing the attacks by Lashkar-e-Taiba (LeT) that killed 166 people.

"Getting Rana is a big deal from the point of view of ensuring justice for the victims of the Mumbai attacks," said an I...