The trial of Sulaiman Abu Ghaith, the son-in-law of Osama bin Laden, took 22 days. A federal jury deliberated for six hours, and after they returned with a guilty verdict last week on terrorism charges, the al-Qaeda propagandist was left facing a life sentence in one of this country’s grim, maximum-security prisons.

For U.S. prosecutors, including Attorney General Eric H. Holder Jr., the case is proof positive of how much more swift and severe the federal courts are when compared to military commissions at Guantanamo Bay, Cuba, where the trials of suspected terrorists continue to play out in seemingly endless procedural hearings.

On Tuesday, Holder traveled to Manhattan to congratulate prosecutors from the Southern District of New York, but also — quite pointedly — to remind his critics that he believes his strategy was right four years ago when he tried to put Khalid Sheik Mohammed, the alleged mastermind of the Sept. 11, 2001, attacks, on trial in Manhattan along with four alleged co-conspirators.

“I think the decision I announced at that time was the correct one,” Holder said. “Many of the problems that we’re now seeing in the military commissions were predicted in the papers I reviewed and helped shape my decision. But that is a decision that has been made. This is not a decision we are going to revisit.”

Holder said of the Abu Ghaith verdict that it “has proven beyond any doubt that proceedings such as these can safely occur in the city I am proud to call home, as in other locations across our nation.”

Holder had to retreat from a planned federal prosecution of Mohammed in the face of bipartisan opposition on Capitol Hill and in New York, where critics argued that the trial was both a security risk to the city and hugely expensive.

Sen. Lindsey O. Graham (R-S.C.), who urged the Obama administration to try Mohammed in a military tribunal, has said that he still does not believe that suspected terrorists should be afforded the legal protections of U.S. federal courts.

“I’m pleased the jury has rendered a guilty verdict in the case of Sulaiman Abu Ghaith,” Graham said. “But the real point is Abu Ghaith, a senior adviser to Osama bin Laden, should have been held as an enemy combatant for intelligence-gathering purposes. Given his high-ranking position in al-Qaeda’s hierarchy, he would have been a treasure trove of intelligence.”

Military proceedings against Mohammed, which the Obama administration restarted in 2011 after the planned New York trial was abandoned, remain in pretrial hearings. And it is unclear when a military jury will be seated and the trial opened, with predictions by some lawyers involved that it will not take place before 2015, at the very earliest.

Since Sept. 11, 2001, eight people have been tried successfully in military commissions at Guantanamo Bay; six of those cases ended with plea agreements. In the same period, there have been hundreds of successful federal terrorism prosecutions, and Justice Department officials insist that there has been no sacrifice of crucial intelligence.

A U.S. official said that the arrests of suspected terrorists in recent years have led to a hybrid approach that has allowed investigators to conduct interrogations for extended periods before defendants are formally charged.

“We’re getting the best of both worlds,” the official said.

Nazih Abdul-Hamed al-Ruqai, also known as Anas al-Libi, was arrested in October after being snatched by U.S. Special Operations forces in Tripoli, Libya, and interrogated for intelligence purposes on a Navy ship in the Mediterranean. He was then taken to New York, where he pleaded not guilty to terrorism charges in federal court in Manhattan in connection with his role in the 1998 bombings of U.S. embassies in Kenya and Tanzania.

Similar tactics have been used in other cases, and Abu Ghaith also was interrogated by U.S. investigators last year, as he was being flown from Jordan to New York, officials said.

“In recent years, the federal government has demonstrated great skill in apprehending foreign terrorism suspects, obtaining high-value intelligence from them, and then proceeding to pursue justice against them through our court system, either by way of guilty pleas or convictions at trial,” Holder said.

Graham and others on Capitol Hill remain resolutely opposed to bringing any detainees held at Guantanamo Bay to the United States for trial. Through repatriations and resettlements in third countries, the Obama administration continues to try to reduce the numbers held at the prison, which currently houses 154 detainees.

But a congressional ban on bringing any detainees into the United States for any reason remains a significant bar to closing the facility before Obama leaves office.

The administration, however, is considering bringing detainees held in Afghanistan to the United States for trial and is weighing whether to put them on trial in the civilian or military systems. Some officials believe that a successful military prosecution of a detainee once held at Bagram Airfield could set a powerful example for the future handling of some Guantanamo detainees.

Adam Goldman and Julie Tate in Washington contributed to this report.