DETROIT - A fellow passenger thought a Nigerian man was just making a routine bathroom trip during a Christmas 2009 flight from Amsterdam to Detroit, but the government contends the man was actually performing a ritual before attempting to detonate a bomb in his underwear.

Umar Farouk Abdulmutallab took a small bag to the bathroom and was gone 10 to 15 minutes, Mike Zantow of Madison, Wis., testified Tuesday as the first witness in Abdulmutallab's terrorism trial.

"It's wasn't real quick. I thought he was freshening up for arrival in Detroit. ... We had less than an hour to go," Zantow said.

A prosecutor said Abdulmutallab was performing a cleansing ritual to prepare for death before returning to his seat to try to detonate a bomb in his underwear on behalf of al-Qaida, an act that badly burned him but didn't destroy Northwest Airlines Flight 253.

Abdulmutallab, 24, is charged with eight crimes, including conspiracy to commit terrorism and the attempted use of a weapon of mass destruction. In his opening remarks to jurors, Assistant U.S. Attorney Jonathan Tukel said the son of a wealthy Nigerian banker believed his calling that day was martyrdom.

"He was preparing to die and enter heaven," Tukel said. "He purified himself. He washed. He brushed his teeth. He put on perfume."

Zantow, who is expected to resume his testimony Wednesday, said he helped move Abdulmutallab out of his burning seat and heard another passenger say: "Hey, dude, your pants are on fire."

Abdulmutallab's attorney, Anthony Chambers, surprised the courtroom when he announced he would save his opening statement until later in the trial. That means the jury will not hear any hint of the defense case, possibly for weeks, while the government calls a parade of witnesses.

Technically, Abdulmutallab is representing himself but he is relying on Chambers as standby counsel. Chambers persuaded him just last week to let him address the jury at the start of trial.

Much of what the prosecutor described was already known from eyewitness accounts, pretrial testimony and government statements. But Tukel offered some new details from inside Flight 253, which had 290 people aboard from 26 countries. He described Abdulmutallab's long bathroom break and how the young man threw a blanket over himself and allegedly attempted to detonate a bomb shortly before the plane landed.

Abdulmutallab pushed a syringe plunger into the chemical bomb, an action that produced a loud "pop" sound, then flames and smoke, the prosecutor said.

"Then all hell broke loose. While the fireball was on him, the defendant sat there. He didn't move. He was expressionless. He was completely blank," Tukel said.

Abdulmutallab was silent at first but then opened up to virtually anyone: a flight attendant, customs officers who removed him from the plane, emergency medical personnel and, finally, FBI agents at a hospital where he was treated for serious burns to his groin, Tukel said.

When a customs officer asked him his affiliation, Abdulmutallab didn't flinch: al-Qaida, he replied, according to the prosecutor.