SEATTLE (AP) — A U.S. soldier charged with killing 16 Afghan civilians is expected to undergo a review of his sanity beginning this weekend.

John Henry Browne, an attorney for Staff Sgt. Robert Bales, said Wednesday his client will participate in the review by Army doctors. It will start Sunday and could last three to seven days.

Bales is accused of murdering Afghan villagers during pre-dawn raids on March 11, 2011. The Army is seeking the death penalty.

Browne previously objected to the sanity review because the Army would not allow the proceedings to be recorded and would not let Bales have a lawyer present, but a military judge ruled in January that Bales must participate.

Such reviews are aimed at discerning a defendant's mental state at the time of the crime and competency to stand trial.