CHICAGO  - A US national who used his Western appearance to carry out surveillance ahead of the deadly 2008 Mumbai siege will be sentenced on January 17, a judge ruled Wednesday. David Coleman Headley, 52, formally admitted to 12 terror charges in March 2010 after prosecutors agreed not to seek the death penalty or to allow him to be extradited to either India, Pakistan or Denmark to face related charges. He is expected to be sentenced to life in prison with no chance of parole.The Mumbai siege, which began on November 26, 2008 and lasted nearly three days, saw 166 people killed and was the deadliest militant onslaught on Indian soil since independence.