He is the silent survivor of the 10-man Isis cell that terrorised Paris in November 2015, refusing all pleas to shed light on the attack that killed 130 people in the French capital or the one in Belgium four days after his arrest.
After spending nearly three years jailed in isolation, Salah Abdeslam went on trial overnight in his hometown of Brussels for a police shootout that he himself fled.
Parisians will be hoping for some new insight into the carnage but Abdeslam has so far shown little inclination to talk.
Kept under 24-hour suicide watch near Paris, the 28-year-old has been transferred to a high-security prison close to France's northern border so that he can be ferried to the Belgian capital's Palace of Justice daily. Hearings are scheduled to last all week in a case related to events four months after the Paris attacks of November 2015.
With a French trial not expected until next year, his Belgian appearance, with alleged accomplice Sofien Ayari, a 24-year-old Tunisian, will be his first moment in public since his arrest on March 18, 2016, close to his family home in the poor, western Brussels borough of Molenbeek.
Both men face up to 40 years in prison for attempted murder linked to terrorism for shooting at Belgian and French police who raided a suspected hideout in the southern Brussels borough of Forest on March 15, 2016.
The man who covered for his getaway with a spray of automatic gunfire died. Abdeslam's escape was short-lived - he was captured in the same neighbourhood where he and many of his Isis (Islamic State) fighter colleagues grew up.
Four days later, Isis suicide attackers struck again, this time at the Brussels airport and subway. In all, that sprawling network of Isis fighters killed 162 people in the two European capitals. Most of the extremists were French speakers, raised in one of the cities they struck. The plot's execution depended upon the success of Isis in wedding crime and religion.
Abdeslam, who with his brother was suspected of dealing drugs from the bar they ran, is the starkest example of that convergence. But in Paris, the trial of three men accused of giving safe haven to the attackers also provides a revealing look at the intersection that made possible two of the deadliest terror attacks in Europe since World War II.
The operational commander of the cell was Abdelhamid Abaaoud, a petty criminal who used his home neighbourhood of Molenbeek in Brussels as a fertile recruiting ground for Isis. Abaaoud even recruited his 14-year-old brother.
But many of the young men who followed him into Isis were small-time criminals themselves, part of the extremist organisation's deliberate attempt to make use of "skills" that include accessing black market weapons, forging documents and handling covert logistics.
When the night of carnage in Paris - November 13, 2015 - was finally over, seven attackers were dead and three were on the run: Abdeslam, Abaaoud and another Molenbeek native named Chakib Akrouh.
Abdeslam called friends in Brussels to drive through the night and pick him up.
Abaaoud also called his cousin, Hasna Ait Belkacem, who lived in a suburb of Paris and vacillated between hard-line Islam and even harder drug use. She was happy to help. She called her dealer. He called another dealer.
It took a few days of sleeping under bushes, but for €150 ($256) wired from Belgium, they secured a room in the Paris neighbourhood of Saint-Denis, near the national stadium they had attacked on November 13.
In the pre-dawn hours of November 18, frantic French investigators tipped off by a friend of Ait Belkacem tracked them to the building and sealed off the neighbourhood.
Abaaoud, Ait Belkacem and Akrouh all died when Akrouh detonated a suicide vest.
Just before his building crumbled to the ground, one of the drug dealers, Jawad Bendaoud, showed up to find out what was happening and explained on live television that he was just "doing a service" by renting out his room. With the cameras still rolling, Bendaoud was taken into custody.
At their trial, fellow dealer Mohammed Soumah explained how he framed the world: Good citizens, delinquents, rapists, and terrorists.
"Me, I don't fit in the terrorist box. I'm a thug, a scumbag," Soumah told the judge. But there he was sitting in the box for terrorism defendants in central Paris alongside Bendaoud.
As for why neither man made the connection between the two Belgians desperate for a hideout amid a massive police manhunt and an outpouring of grief for France's 130 victims, Soumah had another explanation.
"The criminal life goes on," he said.
But the lines between terrorists and criminals are less clear now than ever, said Peter Neumann, director of the International Centre for the Study of Radicalisation.
"Isis is perhaps the first jihadist group that has explicitly targeted this demographic, and they've done it very consciously and especially in Europe," Neumann said. "If you go to Sweden, Norway, Holland, Germany, they will all tell you that 50 per cent-plus of the people who have turned up travelling to Syria or involved in domestic plots have previous criminal convictions, often for petty crime."
The attacks often are interwoven as well. On Friday, a Belgian career criminal was transferred into French custody over allegations that he housed the jihadi who attacked the Thalys high-speed train between Brussels and Paris in August 2015.
The suspect, Youssef Siraj, is also believed to have put up some of the Brussels attackers, according to the Belgian news site DH. The same group allegedly is linked to a raid in the Belgian town of Verviers, where authorities say a jihadi cell was on the verge of a co-ordinated attack against police.
The jihadi who wired the money to pay Bendaoud and Soumah was himself a petty criminal in Sweden before joining the Isis group, a thief who picked up firearms skills during his time in Syria named Mohamed Belkaid. It was also Belkaid who opened fire on Belgian police as they raided Abdeslam's Brussels hideout. He was shot dead in the March 15, 2016, raid.
Abdeslam escaped through a window over the rooftops.
He was traced to a cousin's apartment on March 18, 2016, near his Molenbeek home. Still more members of the cross-border Isis cell struck Brussels on March 22, 2016, including the bombmaker for both attacks. Thirty-two people were killed in Brussels, along with three suicide attackers.
Abdeslam has been imprisoned ever since. His trial will be the first time he is seen in public since his capture.