Published: Jul 29, 2010 7:03 PM EDT
Updated: Jul 29, 2010 3:59 PM EDT

WASHINGTON (AP) - The former superintendent of Arlington National Cemetery says he accepts "full responsibility" for the mix-up of graves at the famous military burial ground.

John Metzler ran the cemetery for 19 years before he was forced out because of the scandal. He told a Senate committee on Thursday that it pains him that his team didn't do its job. He expressed his "sincere regrets to the families."

Missouri Sen. Claire McCaskill said at the hearing that as many as 6,600 graves at Arlington could be unmarked or mislabeled because managers didn't do their job properly.

That's much higher than the estimate last month from Army investigators, who said about 211 remains were affected.

Metzler's former deputy, Thurman Higginbotham, also appeared. Higginbotham says he plans to assert his Fifth Amendment right not
to answer questions.