By Alastair Macdonald and Robert-Jan Bartunek
BRUSSELS (Reuters) - Abdelhamid Abaaoud, suspected planner of the Paris attacks, mocked European frontier controls and boasted of the ease with which he could move between Syria to his Belgian homeland and the rest of Europe.
As police piece together how militants mounted Friday's assaults, evidence that some involved had fought in Syria and were on wanted lists, yet slipped back to kill 129 people, will raise a host of questions on how Europe tracks local Islamists and controls the borders it has opened to half a million Syrian refugees.
Abaaoud, a 28-year-old of Moroccan origin, was the best known of more than 350 Belgians to fight in Syria -- proportionately the biggest contingent from Europe -- and in particular of dozens of young men from the poor Molenbeek district of Brussels to take up arms for Islamic State.
His notoriety was based on videos on social media and, for the past year, his boasts of mounting attacks in Europe.
In a slick online English-language magazine produced by Islamic State in February, Abaaoud, now known as Abu Omar al-Baljiki -- the Belgian -- said he had been in his homeland the previous month planning attacks with two others who had fought in Syria and who died in a Belgian police raid in January.
He had, he said, returned to Syria, despite his face having been well known to police thanks to a much-posted video of him driving a pick-up truck towing the bloodied bodies of prisoners.
"I suddenly saw my picture all over the media, but alhamdulillah (thanks be to God), the kuffar (infidels) were blinded by Allah," he said. "I was even stopped by an officer who contemplated me so as to compare me to the picture, but he let me go, as he did not see the resemblance.
"This was nothing but a gift from Allah."
Boasts like that from one of Europe's most wanted men are likely to fuel debate on stepping up measures like the use of biometric passports, including fingerprint or iris data, that could combat the use of fake documents and human recognition.
A PROMISING STUDENT
Once a student of some promise -- at 12 he won a scholarship to an elite Catholic school miles from his family clothes store in Molenbeek -- he later worked with his father, Omar, but in 2013 vanished suddenly before showing up in Syria.
Omar has since disowned him and accused him of kidnapping his younger brother who, at just 13, was vaunted on social media as becoming the youngest foreign fighter in Syria.
Security officials have said Abaaoud may have first returned briefly to Europe in late 2013 and then returned before the attacks on French magazine Charlie Hebdo this January.
A week later, two of his alleged accomplices were killed in a raid in the eastern Belgian town of Verviers that officials said foiled a plot to kidnap and kill a police officer.
In his online interview, supposedly back in Syria, Abaaoud said he was the only one who traveled with the two dead men, named in Belgium as Sofiane A and Khalid B, both in their 20s, although a third man was arrested in connection with the case.
Asked if the trio, who were pictured together in the online publication Dabiq against a background of blue sky and olive trees, had found it hard to return to Europe, he said:
"We faced a number of trials during the journey. We spent months trying to find a way into Europe, and by Allah's strength, we succeeded in finally making our way to Belgium."
Security officials believe they entered Europe via Greece.
"We were then able to obtain weapons and set up a safe house while we planned to carry out operations against the crusaders.
"The kuffar raided the place with more than 150 soldiers from both French and Belgian special forces units. After a gun battle that lasted about 10 minutes, both brothers were blessed with shahadah (martyrdom), which is what they had desired."
Abaaoud noted that he had previously been in prison in Belgium -- local media have said he was jailed for robbery in 2010 and spent time alongside Salah Abdeslam, the 26-year-old Molenbeek man also sought over the Paris attacks and whose elder brother has been identified as one of seven suicide bombers.
The Abdeslam brothers ran a Molenbeek bar shut down for drug dealing this summer. Both were on the Belgian intelligence services radar as possibly having been radicalized, judicial officials told Le Soir newspaper.
The elder, Brahim, had traveled to Turkey hoping to reach Syria but was deported by the Turks and questioned on his return. So too was Salah, though it is unclear if he had ever tried or succeeded in traveling to Syria.
"ALLAH BLINDED THEIR VISION"
After the Verviers raid, Abaaoud told the Dabiq online site: "They gathered intelligence agents from all over the world ... to detain me. They arrested Muslims in Greece, Spain, France, and Belgium in order to apprehend me." None of those were associates, he said, and he was able to make it back to Syria.
"Allah blinded their vision and I was able to leave and come to Sham (Syria) despite being chased after by so many intelligence agencies. All this proves that a Muslim should not fear the bloated image of the crusader intelligence. My name and picture were all over the news yet I was able to stay in their homeland, plan operations against them, and leave safely."
French and Belgian security officials believe Abaaoud has been closely involved with at least three other attacks. He was in contact with Mehdi Nemmouche, the Frenchman facing trial for killing four people at Brussels' Jewish Museum in May 2014.
He is suspected of a role in a failed attack on a church in a Paris suburb in April this year and in an abortive attempt by another man to shoot dozens of people aboard an Amsterdam-Brussels-Paris Thalys express train in August.
A French judicial source said a French jihadist questioned on his return to France from Syria in August said he was ordered by Abaaoud to travel via Prague to avoid detection and to scout out a soft target in Europe -- such as a concert hall -- to ensure a high death toll.
Roland Jacquard, a French security expert, said Abaaoud was part of a French-speaking brigade of Islamic State in Raqqa, which was targeted by French air strikes last month, and that he was subordinate to Salim Benghalem, a Frenchman on global most wanted lists and may have ultimately ordered the Paris attacks.
Omar Abaaoud, whose own father arrived in Belgium from Morocco four decades ago to work in the coalmines, told Belgian newspaper Het Laatste Nieuws in January after the Verviers raid:
"We had a good, I'd say a fantastic life. Abdelhamid wasn't a difficult child and a good manager. But then he all of a sudden left for Syria.
"I think about why he left every day and why he turned so incredibly radical at such short notice. There will never be a real answer ... I don't understand why he wanted to attack Belgium. Our family owes everything to this country."
(Additional reporting by John O'Donnell in Frankfurt and John Irish in Paris; Editing by Sonya Hepinstall)