A nine-day military hearing into the deadly friendly fire bombing of Canadian troops in Afghanistan ended with two U.S. pilots offering apologies -- but insisting they were not at fault.

Majs. Harry Schmidt and William Umbach face weeks or months awaiting the hearing officer's recommendation on whether they should be court-martialed for involuntary manslaughter, aggravated battery and dereliction of duty.

The April 17 bombing occurred as Schmidt and Umbach, in their F-16 fighter jets, were returning from a patrol over Afghanistan. The pilots saw weapons fire from below, and fearing it was from Taliban forces, Schmidt attacked with a 500-pound laser-guided bomb.

The weapon hit Canadian forces conducting live-fire exercises. Four soldiers were killed and eight were wounded.

During the military hearing at 8th Air Force headquarters here, the Air Force called more than a dozen witnesses over eight days, suggesting the pilots could have flown away but instead recklessly disobeyed orders and ignored briefings describing the location of allied troops.

Defense attorneys argued the pilots thought they were under enemy attack and that they were never told allies might be in the area conducting exercises that night. They also suggested Air Force-issued amphetamines may have clouded the pilots' judgment.

In his statement Thursday, Schmidt, who dropped the bomb, called the accident a tragedy committed in the "fog of war."

"I was called upon to make a perfect decision in a rapidly unfolding combat environment," he said in a steady voice. "I had to make that decision with what I now know, with the acuity of 20-20 hindsight, was imperfect information."

Umbach, the mission commander, began his statement by reading the names of the dead and wounded. "Since the seventeenth of April, not a day has passed that I have not thought of that night," he said.

"Maj. Schmidt and I were doing our best to protect ourselves in a situation where we honestly believed we were under attack," he said.

Marley Leger, wife of Sgt. Marc Leger, one of the four Canadian dead, said afterward that she believed the hearing was fair. She would not discuss what she believes should happen to the pilots.

Specially painful, she said, was listening to testimony from survivors of the bombing, who described what they and her son were doing in the moments before the bomb blast.

"Every single time his name was mentioned tore a little piece away from me, every single time," she said. "Specifically in the beginning of the hearing, when the boys were talking about what was happening on the ground was very, very difficult. Because Marc's name was mentioned so often."

Families and friends of the victims watched via television hookups from a separate room; families of the pilots from another room, reporters from still another.

Defense lawyers David Beck and Charles Gittins also submitted much of their case in writing Thursday, rather than calling witnesses. Among the documents were statements from two physicians that Dexedrine, the "go pills" issued by the Air Force, are banned from use by civilian pilots and could impair judgment.

Air Force officials have said the pills are for only used voluntarily in doses small enough to produce just a "mild stimulant effect" on missions that can last longer than 10 hours.