SAN DIEGO - Charges against two Marines accused in a drill instructor's drowning last year should be dismissed, an investigator ruled, because the death was the result of "an institutional failure."

Staff Sgts. David J. Roughan and Fernando Galvan were charged in the August 2005 death of Staff. Sgt. Andrew Gonzales, who drowned during a water survival course at the Marine Corps Recruit Depot in San Diego.

Lt. Col. Paul L. Starita headed up an investigation in March to recommend whether Roughan and Galvan should face courts-martial on charges of manslaughter, negligent homicide and dereliction of duty.

Starita recommended that the two Marines should not be prosecuted and accused the Marine Corps of oversights that led to Gonzales' death, The San Diego Union-Tribune reported Tuesday.

"This case is absolutely tragic because Staff Sgt. Gonzales' death was preventable," Starita wrote, and his death "resulted from an institutional failure."

If Galvan and Roughan were to be court-martialed, Starita wrote, "then so should each and every individual that could have controlled or supervised the conduct of the 'work-up' course and failed to do so."

The course involved instructors placing Marines in underwater holds and making them perform escape maneuvers.

Poolside equipment that might have saved Gonzales wasn't used or wasn't working properly, according to a Marine Corps report. The report also indicates that no lifeguards were watching for Marines in trouble.

Starita delivered his recommendation to Brig. Gen. John M. Paxton, Jr., the depot's commander. Paxton will decide if the men should be tried in a military court, where a conviction on all charges could send each to prison for 20 years.

Gonzales' widow, Michelle, agreed that there was an institutional failure, but said she believed that individuals should be court-martialed.