Shane Schmidt, a private security guard in Iraq who raised questions about lax government oversight of U.S. defense contractors when he accused his boss of randomly shooting at, and perhaps killing, civilians in Baghdad, died Sept. 19 at a hospital in Marshfield, Wis. He was 33.

Mr. Schmidt, a Haymarket resident who was visiting family in Wisconsin, was crossing a road near Marshfield just after midnight when he was struck by a vehicle. He was taken to a nearby hospital, where he died, according to a news release from the local sheriff's department. The incident was under investigation.

Mr. Schmidt was a Marine Corps sniper who served two tours in Afghanistan before taking a job in 2004 with Triple Canopy, a Herndon-based company and one of the largest defense contractors working with the U.S. military in Iraq.

For $500 a day, he provided protection for American bases and visiting military personnel and contractors.

On July 8, 2006, the former Marine was one of four Triple Canopy employees traveling in an armored sport-utility vehicle to the Baghdad airport.

One of the four, shift leader Jacob C. Washbourne, was scheduled to leave Iraq the next day for a vacation in the United States. "I want to kill somebody today," he said as he cocked his gun, according to the other three men in the vehicle.

In two separate encounters later that day, Washbourne fired unprovoked into the windshields of an occupied taxi and pickup truck, said Mr. Schmidt and a colleague, former Army Ranger Charles L. Sheppard III. They suspected that civilians had been seriously injured or killed, although they didn't know.

"I do not have a problem killing bad guys, that's what we do," Mr. Schmidt told the New York Times in 2006. "But murdering innocent civilians? That is wrong, and justice has to be served."

Mr. Schmidt and Sheppard, who said they feared reprisal from Washbourne, waited two days until he had left the country before reporting what they had witnessed to top Triple Canopy managers.

An internal investigation followed. Washbourne denied every accusation. Triple Canopy fired Mr. Schmidt and Sheppard, saying that they had violated company policy by failing to report the shootings right away.

The fourth guard, Fiji native Isireli Naucukidi, reported the July 8 incidents immediately - offering an account that differed slightly from the others - and then left Triple Canopy on his own.

"I couldn't stand what was happening," Naucukidi told The Washington Post in 2007. "It seemed like every day they were covering something up."