DETROIT – In a 1½-hour opening statement Tuesday, the government laid out its case against underwear bombing suspect Umar Farouk Abdulmutallab, telling jurors the defendant was on a mission from al-Qaida to blow up an American airliner — and to make sure that the attack happened on U.S. soil.

Abdulmutallab, prosecutors said, did as he was told and prepared to die, making several trips to the bathroom, where he brushed his teeth, put on cologne and prayed before executing his plan on Northwest Flight 253.

“His mission, his goal, his sole reason for being on Flight 253 was to blow it up … ,” Assistant U.S. Attorney Jonathan Tukel told jurors of the Nigerian defendant. “He thought he would end up in heaven because he would be a martyr.”

Abdulmutallab, though, did not end up in heaven, but in a federal courtroom in Detroit, where the 24-year-old baby-faced defendant appeared for day one of his terror trial in a traditional, African gray tunic with gold and cream embroidery.

Despite his recent outbursts in court, including proclamations that Osama bin Laden is still alive, Abdulmutallab said nothing Tuesday, and even opted out of giving an opening statement. His standby-lawyer Anthony Chambers was supposed to deliver opening statements, but at the last minute, Abdulmutallab requested a side-bar conference, delaying the trial by an hour. When the defense returned to the courtroom, Chambers said that there would be no opening statement, but that there could be one at a later date.

Tukel’s opening statement, meanwhile, provided the first, detailed account of what happened inside the aircraft on Christmas Day 2009, the day that Abdulmutallab allegedly tried to blow up a Detroit-bound airliner with explosives hidden in his underwear. Tukel explained to jurors how the suspect behaved in the moments before he allegedly detonated his bomb, which happened while the aircraft was flying roughly 9,000 feet over Woodhaven, Mich.

According to Tukel, as the plane approached Detroit, Abdulmutallab spent increasing amounts of time in the lavatory praying and purifying himself. Then he returned to his seat, pulled a blanket over his head, and pressed the plunger on the bomb. First came a loud pop, then smoke, then the fireball in the suspect’s lap, Tukel said.

“After that, all hell broke loose,” Tukel said, noting that several passengers tried to put the fire out, but nothing worked until flight attendants doused it with fire extinguishers. Abdulmutallab was eventually escorted to the business class section, where he sat naked from the waist down for the rest of the flight, he said.

Witnessing it all was Wisconsin passenger Michael Zantow, the first government witness to testify in the case. Tuesday, he testified that after he heard a loud pop that sounded like firecrackers, he heard the passenger seated next to Abdulmutallab say: “Dude, your pants are on fire.” He said the passenger repeated the phrase several times, but that Abdulmutallab never responded.

A flight attendant came up to see what was happening, Zantow said. When she learned that Abdulmutallab’s pants were on fire, things started happening quickly, he said. Passengers yelled to get his seat belt off and get his pants off to see what was going on. Four passengers lifted him out of his seat and put him on the floor of the plane.

That’s when Zantow said he caught a glimpse of “underwear I hadn’t seen before.” He described it as “bulky,” and said it reminded him of what his child’s pull-ups looked like when they were full — a comment that drew laughter from several jurors.

“They were bulky and they were burning,” Zantow testified.