One of the Army’s most prominent lawyers has been appointed chief prosecutor in the Office of Military Commissions, a clear signal that the Obama administration is determined to move forward briskly with tribunals at Guantanamo Bay, Cuba.

Brig. Gen. Mark Martins, a Harvard Law School graduate who is commander of the Rule of Law Field Force in Afghanistan, will take up his new post Oct. 1, the Pentagon said in a statement Thursday.

The current chief prosecutor, Navy reservist Capt. John Murphy, will return to civilian life and his job as an assistant U.S. attorney in Louisiana.

“I think this is an inspired choice, and not just (or even mainly) because of Martins’ sterling resume,” wrote Jack Goldsmith, a Harvard Law professor and former Justice Department lawyer, on the Lawfare blog. “As much as anyone I know, Martins has thought deeply about military commissions — their history, the legal and political problems with commissions as originally conceived after 9/11, their virtues and drawbacks in the post-9/11 environment, and most importantly the need for commission trials to be conducted in a manner that is legitimate and widely perceived to be so.’’

Martins will oversee the capital trial of Khalid Sheik Mohammed, the self-proclaimed mastermind of the Sept. 11, 2001, attacks, and four co-defendants who were re-charged late last month.

Attorney General Eric H. Holder Jr. reluctantly returned the prosecution of Mohammed and the other defendants to the military after the Obama administration’s plans to hold a trial in federal court in New York ran into fierce congressional and local opposition.

Military prosecutors also recently charged Abd al-Rahim al-Nashiri, one of 15 high-value detainees at the U.S. military detention center, with murder, terrorism and other violations of war in connection with the October 2000 attack on the USS Cole in Yemen.

With the administration unable to prosecute Guantanamo detainees in civilian court because of congressional opposition, there are likely to be a significant number of military commissions at Guantanamo. An interagency task force that examined the cases of all Guantanamo detainees had recommended that 36 should be prosecuted in federal court or military commissions.

Since the military detention center opened in 2002, six commission cases have been completed, resulting in four plea bargains, a short sentence and a guilty verdict. Two of those six detainees have been released, and three more are scheduled to be sent home over the next few years as a result of the pleas.

Administration officials have said that they want to pick up the pace, and Army insiders said Martins is a driven officer who has served with distinction on sometimes punishing assignments.

Martins, who finished first in his class at the U.S. Military Academy at West Point, served under Gen. David Petraeus in Iraq and Afghanistan, where he worked on detention issues and also helped reform the local justice systems.

“He’s our best lawyer, and it signals a new era at Guantanamo,” said an Army lawyer who spoke on the condition of anonymity to discuss a superior officer. “He is a very serious guy.”

Martins co-led the Detention Policy Task Force set up by President Obama that recommended reforms to a military commissions system that was widely criticized by human rights groups. Some of those recommendations were incorporated into the 2009 Military Commissions Act.