A former commander of the USS John S. McCain pleaded guilty Friday to dereliction of duty when the destroyer collided with a commercial tanker, killing 10 sailors and injuring five in the Straits of Singapore last August.

Cmdr. Alfredo Sanchez, who has served in the Navy for more than 20 years, testified during a special court-martial at the Washington Navy Yard, Stars and Stripes reported.

“I am ultimately responsible and stand accountable,” Sanchez said. “I will forever question my decisions that contributed to this tragic event.”

Per disciplinary proceedings, Sanchez agreed to retire from service, forfeit $6,000 in wages, and was issued a letter of reprimand.

Sanchez claimed responsibility for the deadly collision. He said had failed to put a well-rested, well-trained crew in place to steer the destroyer into the Straits.

The former commander, who was immediately reassigned after the collision, initially faced negligent homicide charges, CBS News reported.

According to Sanchez, an 18-year-old undertrained helmsman had been navigating the destroyer, known as "Big Bad John," leading up to the collision.

The Navy judge, Cmdr. Charles Purnell, who presided over Friday’s court-martial, singled out the failure to navigate the console as the “overarching failure.”

Sanchez acknowledged his failure to provide a more rigorous training.

More than a dozen relatives of the fallen crewmembers attended Friday’s hearings, reading impact statements, and calling out the Navy for negligence, Stars and Stripes reported.

“I am haunted by it every day,” said Karen Doyon, mother of Petty Officer 3rd Class Dustin Doyon, 26, of Connecticut. “This is a tragedy that should have never happened.”

The USS John S. McCain is named for the father and grandfather of U.S. Sen. John S. McCain III, R-Ariz., who like the senator had distinguished careers in the Navy.