SEATTLE — The U.S. soldier charged in the shooting deaths of 17 Afghan villagers last month will not participate in an Army review aimed at determining his mental state, his attorney said Friday.

Staff Sgt. Robert Bales was expected to face what’s called a “sanity board” examination by Army doctors from Walter Reed Army Medical Center, seeking to establish whether he’s competent to stand trial and what his mental state was at the time of the March 11 pre-dawn massacre in two southern Afghanistan villages.

But his civilian lawyer, John Henry Browne, said Friday he instructed Bales to invoke his Fifth Amendment right to remain silent because the Army will not allow Bales to have an attorney at the sanity board review and will not allow the examination to be recorded.

“A member of the military does not give up constitutional rights by being in the military,” Browne wrote in an email to reporters.

Maj. Chris Ophardt, a spokesman at Joint Base Lewis-McChord south of Seattle, said that typically, such examinations are not recorded and defendants do not have their lawyers present. Such proceedings are medical, not legal, he said.

“They want to make sure the board can ask the questions they need to ask to make a fair determination, without any outside influence,” Ophardt said.

The sanity board had been expected to explore such issues as Bales’ deployment history, including a concussion that Browne has said he suffered during one of his three prior deployments to Iraq, as well as any prescription medication he may have been taking and whether some sort of psychotic episode led to the shooting.

In most cases, the only information given to prosecutors following a sanity board review consists of a brief diagnosis and the answers to three yes-or-no questions: Was the defendant suffering from a mental disease at the time of the offense? Was the defendant able to appreciate the wrongness of his or her actions? Is the defendant currently suffering from a mental disease and thus unable to understand the legal proceedings?

The answers to those questions help prosecutors decide whether it’s fair to have the defendant stand trial, Ophardt said.

It wasn’t immediately clear if the sanity board would proceed without Bales’ cooperation.