Headley Timeline: From terrorist to approver (To go with Headley exposes Pakistan's role in 2008 Mumbai terror strike)

David Headley grew up in a strict Pakistani boarding school before becoming a barman at his family tavern in Philadelphia in the US and making contacts with Pakistani spy agencies who made him play a key role in the 2008 Mumbai terror attack.

In 1998, he was jailed for two years for smuggling heroin into the US from Pakistan. After the jail term, he went to Pakistan to conduct undercover surveillance operations for the US Drug Enforcement Administration.

November 26-28, 2008: Ten Pakistani terrorists sail into India and kill 166 people over three days at multiple targets. Headley confessed to have scouted each of these targets earlier.

February 2006: Headley changes his name from the Muslim Daood Gilani to give himself an American identity, apparently to enter India and other countries easily.

2006-08: He visits India five times from September 2006 to July 2008 to video various potential targets for the terrorists.

March 2009: Even after the Mumbai carnage, Headley returns to India for his sixth trip to plot another attack, with possible targets being the National Defence College in Delhi and Chabad houses in several cities.

October 3, 2009: Nearly a year after the Mumbai carnage, Headley, on his way to Pakistan, is arrested at O'Hare International Airport in Chicago.

December 2011: India's National Investigating Agency files charges against Headley, his Pakistani-Canadian accomplice Tahawwur Rana, Lashkar founder Hafiz Saeed and seven others for conspiring to attack India.

January 24, 2013: He gets 35 years in prison in a court in Chicago for the Mumbai attack and a foiled attempt to strike at the office of Jyllands-Posten, a Danish newspaper that published caricature of Prophet Mohammed.

December 10, 2015: The special anti-terror court in Mumbai pardons Headley after he agrees to be an approver in cases related to the 2008 attack.

February 8, 2016: Headley testifies before a special court in Mumbai from a US prison through video conference.