A senior al-Qaeda member is set to be sentenced Friday in a Brooklyn court for conspiring to kill two American service members 15 years ago in Afghanistan and later plotting to bomb the U.S. Embassy in Nigeria.

Ibrahim Suleiman Adnan Adam Harun, or Spin Ghul as he was known to fellow militants, faces life in prison. His conviction on terrorism charges in March is the first of 30 secured by federal prosecutors since President Trump took office.

But the case highlights a predicament for the administration. The federal court system, which Attorney General Jeff Sessions has criticized as being too lenient with terrorists captured overseas, is far more efficient than the military tribunals run out of Guantanamo Bay.

Since Sept. 11, 2001, federal prosecutors have used civilian courts to bring more than 500 international terrorism cases, obtaining convictions in more than 400 to date, according to Fordham University’s Center on National Security. Most of the others are pending. None of the alleged 9/11 conspirators, who were indicted in 2009 and remain at Guantanamo, has been tried. The earliest that might happen is 2019.

“There’s no question that the U.S. court system has been the most effective option for prosecuting international terrorism cases,” said Mary McCord, a former acting assistant attorney general for national security during the Obama administration and now a visiting professor at Georgetown University Law Center.

Trump last month issued an executive order that reinforces the use of Guantanamo as a detention facility, formally rescinding Barack Obama’s order to close the prison. It instructs Defense Secretary Jim Mattis to develop recommendations for handling suspected militants captured overseas, including procedures for possibly bringing them to Guantanamo. Sessions supports the new order and has indicated a desire to see the military court system improved so it can become a viable option for prosecutions.

The Guantanamo cases have stalled for a number of reasons, including that some of the defendants were tortured while in U.S. detention. A bigger challenge is that the system is being created as prosecutors are trying to use it. The procedures are new and untested, judges are unsure about how to apply them, and there are few legal or administrative precedents to go by.

Observers note, however, that civilian courts have clear advantages over the tribunals. One is the ability for prosecutors to use material support and conspiracy statutes, which in the military system have faced unresolved questions about the scope and constitutionality of the military courts’ jurisdiction over domestic laws.

Another is the detention facility’s reputation. It has come to be associated with the mistreatment of detainees and a lack of legal and human rights standards.

European allies such as Italy, where authorities detained Spin Ghul in 2011, have indicated they would refuse to transfer terrorist suspects to the United States to be tried at Guantanamo Bay. The Italians allowed U.S. agents and prosecutors to interrogate him, obtaining a confession that was key to his conviction. That option would probably not have been available had his case been handled in a military court, officials say.

Spin Ghul’s attorneys argue that he should be shown leniency at his sentencing Friday, noting he was tortured while detained in Libya for six years before his arrival in Italy and has mental health problems. In Afghanistan, they say, he was doing what soldiers do — that his offenses did not constitute war crimes.

The battle that led to Spin Ghul’s conviction occurred April 25, 2003. The commander of Firebase Shkin, which housed about 100 American troops in eastern Afghanistan, was notified of 15 to 20 al-Qaeda militants approaching from across the Pakistani border, according to court testimony. The group included Spin Ghul.

The fighters climbed a hill and observed a vehicle carrying U.S. troops. One of the Americans got out and suddenly, he recalled, “the ground erupted around me” with small-arms fire.

Spin Ghul saw he had “a direct shot” at U.S. troops higher up the hill. “I opened my Kalashnikov and started firing,” he recounted, according to court records.

As the firefight continued, two Americans moved to call in air support. They were taking fire from all sides and ran for cover toward an armored Humvee. A moment later, Airman 1st Class Raymond Losano slumped against the vehicle’s door. He was holding his face, blood gushing from his mouth. Losano died later that day.

Pvt. Jerod Dennis had gone missing. Another soldier found him down a hillside, his pants soaked with blood. Dennis, too, died that day.

The battle left Spin Ghul seriously injured. In the fray, he left behind his leather-bound Koran.

Back in Pakistan, Spin Ghul asked Abu Faraj al-Libi, a senior al-Qaeda commander, to be entrusted with a more ambitious operation. He wanted to attack the U.S. Embassy in Nigeria.

In August 2003, Spin Ghul traveled to Abuja, the capital, but failed to buy explosives. Fearing capture, he fled to Niger and then to Libya, where he was detained in 2005. After his release six years later, he was put on a boat with 1,200 refugees bound for Italy. Authorities there contacted the FBI in New York.

“Jaws dropped when the Italians told us they had somebody in custody they believed to be Spin Ghul,” said a former U.S. intelligence official. “He was a core al-Qaeda guy who had historical and current connections, on the continent and in South Asia.”

In September 2011, a team of prosecutors and FBI agents flew to Agrigento in Sicily, where Spin Ghul, about 5 feet tall, was held in a jail cell in a football field-size courtroom designed for Mafia megatrials. Prosecutor Shreve Ariail read him his Miranda rights and Spin Ghul talked for three days, describing his role during the battle in Afghanistan. It amounted to a confession.

The Justice Department supported the case after receiving a letter from the military commission at Guantanamo Bay, where prosecutors were persuaded that Spin Ghul would never be extradited to stand trial there and that if he were prosecuted federally, he might produce evidence useful in their cases.

Italy extradited him in October 2012, but it took time to develop evidence. A key break came when investigators found a soldier who had brought home from Afghanistan a Koran bearing Spin Ghul’s fingerprints.

The trial in March lasted almost two weeks. Spin Ghul did not appear. A video feed was relayed to his jail cell in Manhattan.

The prosecution closed its case by detailing the attack that killed Losano and Dennis. A photograph of Osama bin Laden faced the jury.

The defense made no closing remarks, and the jury took two hours to deliberate. Spin Ghul was found guilty on all counts.