The 25-year-old Nigerian man who strapped a dud explosive into his underpants and tried to set it off as his flight neared Detroit was sentenced to life in prison Thursday. Umar Farouk Abdulmutallab’s ill-fated attempt at martyrdom went awry on the Christmas Day flight three years ago when the bomb failed to detonate. Passengers on Northwest Airlines Flight 253 tackled him after the bomb caused a small fire that injured his groin. Abdulmutallab told the FBI that he wanted to die for his Islamic faith, and that he traveled to Yemen before his attempted attack to try to meet with al-Qaeda leaders. Abdulmutallab, who pled guilty back in October, appeared calm as his sentence was pronounced, sitting back in his chair with his chin in his hand.