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A small-time American drug dealer-turned-terrorist plotter who helped plan a brutal 2008 attack on Mumbai, India, will learn whether his wide-ranging cooperation with U.S. investigators will earn him any leniency in sentencing.

Fifty-two-year-old David Coleman Headley faces a maximum life prison term when U.S. District Judge Harry Leinenweber sentences him Thursday for his role in a three-day rampage in which 10 gunmen from a Pakistani-based militant group fanned out across Mumbai, attacking a crowded train station, the landmark Taj Mahal Hotel and other targets. Around 160 people were killed, including children.

Prosecutors are asking for a relatively lenient term of 30 to 35 years, which leaves open the possibility Headley one day could go free. Headley seemed to leap at the chance to spill secrets following his 2009 arrest.