On Thursday, it was the turn of Hamza Attou and Ali Oulkadi to give evidence at the Paris attacks trial. Both are suspected of having helped Salah Abdeslam, the only member of the Paris terror squads still alive, to avoid arrest. Neither man is imprisoned. They sit in the open, in front of the prisoners' enclosure. They answered questions at the bar in the special criminal court.
Hamza Attou worked in Les Béguines, the Brussels café run by Brahim Abdeslam.
No, he did not notice any signs of radicalisation in either Brahim or his brother Salah. "They weren't religious. They didn't pray."
Brahim Abdeslam blew himself up on the night of the Paris attacks. Salah returned from Paris that same night in a car in which Hamza Attou was a passenger. Salah Abdeslam is one of the accused in this trial. He was sitting just inches from the witness as he spoke.
Hamza Attou's job in the café was to sell shit. Brahim Abdeslam provided bars of haschich which Attou passed on to the clients in exchange for a commission. He may have been his own best customer, admitting to a consumption of "seven or eight joints per day, minimum".
He never saw Islamic State propaganda videos in the café, nor was he aware of other clients watching such material.
"We watched films. The computer was used a lot for music. With YouTube. That's all I can tell you."
Faced with the incredulity of one of his questioners, Hamza Attou answered the lawyer bluntly, "I'm not here to make you believe me. I'm here to tell the truth."
Attou is 27 years old. He will go to jail for six years if he is found guilty.
Same facts, different version
Ali Oulkadi is ten years older, and he's facing two decades behind bars because he is suspected of having hidden Salah Abdeslam on his return from France, knowing that he was aiding a terrorist.
Oulkadi was a regular at Les Béguines. He knew the Abdeslam brothers well. He did notice a change in Brahim, early in 2015.
"He said we didn't have the right to live in Belgium, but should move to a Muslim country." Brahim Abdeslam argued that a suicide attack was not really suicide. "But nobody took him seriously.
"He was a very good friend, Brahim. But he was never a violent person," according to Ali Oulkadi.
A radical view of radicalisation
Thursday's other testimony was provided by Olivier Vanderhaegen, a Belgian official who spent six years wrestling with the problem of radicalisation in the Brussels suburb of Molenbeek, home to many of the 2015 attackers and their alleged aides.
With a hair-do that would hardly disgrace a Commanche, and a chest-length beard, Vanderhaegen gave the court a jargon-free lesson in street cred.
Radical Islam, he found, generally has little to do with religion. "I met very few 'radicals' who spoke about their belief in God. You can forget about the outward signs. They mean nothing."
A 'radical' is simply somebody who feels fundamentally out of phase with the society which surrounds him. It doesn't have to be violent, but it can become absolute.
In Molenbeek, where youth unemployment skirted the 50 percent mark in 2015, "social exclusion" was not an extraordinary feeling.
The jobless young formed tribes, got involved in crime. "If someone came along with a plausible mix of Islam and madness, he would find a few supporters, motivated either by despair or defiance.
"A woman can't get a job because she wears the veil? If nobody is prepared to compromise, that can become a problem. Not violent, but socially very dangerous.
"Some people believe that society discriminates against Islam," Vanderhaegen continued. "Then they accept a narrative of victimisation. That gives them access to a community and a social identity.
"But you have to avoid thinking social causes explain everything.
"It's complicated. We still don't really know what 'radicalisation' means."
The trial continues.