Salah Abdeslam, the man prosecutors believe is the sole survivor of the Islamist group that attacked Paris last November, appeared before a French investigating judge on Friday, but refused to say anything about the assault in which 130 people were killed.
Abdeslam, a French national born to Moroccan-born parents in Belgium and raised there, was brought under heavily armed escort to a court in central Paris from his solitary-confinement cell in a high-security prison outside the capital.
But what was supposed to be the first proper interrogation of the 26-year-old since he was transported by helicopter to France from Belgium in late April was cut short after he refused to talk.
Frank Berton, his lawyer, said Abdeslam, who was captured in Brussels and extradited to France, was upset about being kept under day-and-night watch inside his cell at Fleury-Merogis prison, south of Paris.
"What I can say is he's particularly upset by the camera surveillance in his cell, something that is illegal under the law as it stands," Berton told reporters.
"He can't handle being watched 24 hours a day and that's causing a problem psychologically I believe."
Abdeslam's refusal to speak was unexpected as his lawyer Berton had said last month he was ready to speak after transfer to France, where he was officially placed under investigation on 27 April on counts of suspected terrorism and murder.
Abdeslam is believed to be the sole survivor of the 13 November attack by Islamist gunmen and suicide bombers, including his brother, for which the Islamic State militant group that controls large parts of Syria and Iraq claimed responsibility (See: France under emergency: terrorists kill over 120 in multiple attacks). Investigators suspect him at least of having played a logistics role in the assault on a football stadium, several cafes and the Bataclan concert hall, where 90 rock fans died.
Abdeslam was Europe's most wanted fugitive until his capture in Brussels on March 18 after a four-month manhunt. He had fled France by car on the night of the attacks, passing through road police checks before his name was circulated as a suspect.
Lawyers representing victims of an attack in which hundreds were also injured voiced frustration but not surprised.
"This just proves he's somebody who'll never cooperate with the justice system. We never did and never will trust him," said lawyer Samia Maktouf.