Sources: Pilots may face criminal charges in friendly fire deaths

WASHINGTON (CNN) -- Pentagon sources say two U.S. Air National Guard pilots could face criminal charges following an investigation into the accidental bombing of Canadian troops in Afghanistan last April.

The results of the investigation are expected to be released Friday at the headquarters of the U.S. Central Command in Tampa, Florida, Pentagon officials said Thursday.

Four Canadian soldiers were killed and eight were injured when a 500-pound bomb from Maj. Harry Schmidt's F-16 hit their position at about 2 a.m. near Kandahar on April 18.

Those sources say Schmidt, a former Navy Top Gun instructor, told investigators he was not briefed that Canadian forces were exercising in the area, and that he had mistaken their practice mortar rounds for enemy anti-aircraft fire.

The Canadians were operating in an established training area and aircraft were restricted to altitudes above 10,000 feet to avoid any incidents.

Sources say the pilots requested permission to attack the site where they saw the ground fire, but permission was denied.

Instead, sources say, they were told to "mark" the location for possible attack, but then Schmidt dropped his bomb in "self-defense" when he had mistaken the live-fire exercise for threatening ground fire.

Both F-16 pilots -- Schmidt, the "wingman" and his "flight leader," Maj. William Umbach -- were found to have violated the rules of engagement for responding to potentially hostile fire, sources say.

The two F-16s were flying together and sources say Umbach was found to have failed to control the actions of his wingman.

Pentagon officials said the pilots were flying at 23,000 feet, well out of danger from small arms or anti-aircraft guns, and that the proper procedure would have been to clear the area to assess the threat.

Pentagon officials say that three other people in the "briefing chain" may be disciplined, but note that even if the pilots were not informed of the Canadian exercise, it would still not excuse violating the rules of engagement.

The investigation of the accident was conducted with the participation of the Canadian government.

The investigation report recommends an Article 32 hearing, a military procedure similar to a civilian grand jury proceeding. It could result in a number of courses of action, including a variety of charges, military sources told CNN on Wednesday.

Pentagon sources say Schmidt, 37, of the Illinois National Guard was a former Navy pilot who joined the Air National Guard after he left the Navy last year.

He is a decorated combat veteran, whose career included a stint as an instructor at the Navy's prestigious "Top Gun" school for combat pilots.

He graduated from the U.S. Naval Academy in 1987, and he was a lieutenant commander when he left the Navy in December.

An F-18 pilot, Schmidt earned the Navy and Marine Corps Commendation Medal twice, the Navy Achievement Medal twice and the Air Medal three times.