The arrest on Friday of Salah Abdeslam, who is suspected to have been the head of logistics for the Paris terrorist attacks in November, offers French and Belgian investigators the opportunity to gather new information about how the atrocity was planned and carried out.

For months, the police have been criticised for not being able to the prevent the attacks and failing to stop the expansion of what is now suspected to be a web of ISIS sleeper cells spread throughout continental Europe.

The Paris attacks, which killed 130 people and injured hundreds more, shocked the world, as they struck the heart of Europe and showed the reach and organisation of ISIS (also known as the Islamic State, Daesh, or ISIL).

Most of what is known about the attacks is contained in a 55-page report from the French antiterrorism police. The New York Times obtained a copy of the report, which shows that the attackers and those who aided them knew how to exploit the European border system, how to make certain type of bombs, and how to overwhelm the police.

A New York Times article discussing the report suggests that questions about the number of people involved, how many were trained in Syria, and what kind of encryption the terrorists used to hide their communications remain unanswered.

Candles outside the French Embassy in Vilnius, Lithuania, on November 14 for the victims of the attacks in Paris. AP Photo/Mindaugas Kulbis With the Paris attacks, ISIS moved away from its usual types of targets, such as security establishments and places with links to Israel. But, according to The Times, in one of the group's online magazines, a senior ISIS member advises against picking specific targets and to instead, "Hit everyone and everything."

In January, Europol, the European Union's law-enforcement agency, announced the launch of a Europe-wide "Counter Terrorism Centre," which was created in response to the attacks in Paris and which aims to improve information sharing among security forces of all European countries.

The scope of the failure of European security forces and the need for them to work together became clear when it was revealed that at least three of the attackers were wanted on international warrants but were able to travel between Europe and the Middle East.

Alain Chouet, a former head of French intelligence, told The Times: "We don't share information. We even didn't agree on the translations of people's names that are in Arabic or Cyrillic, so if someone comes into Europe through Estonia or Denmark, maybe that's not how we register them in France or Spain."

Increasingly well-organised attacks

The report shows how well prepared the terrorists were and that they knew to combine three attacks (suicide bombers at the Stade de France stadium and in cafes; shootings around Paris; and hostage-taking) to stretch the emergency services.

Police officers at the scene of a security operation in the Brussels suburb of Molenbeek in Brussels on Friday. Reuters/Francois Lenoir The explosive used by one of the suicide bombers was a peroxide-based device, which has become the staple explosives for ISIS attacks. The bomb is made with products easily available, like hair bleach and nail varnish remover, but is quite hard to assemble, which shows those involved had received training.

But it is the attack on the Bataclan theatre, especially, which shows the attackers' level of planning. Two gunmen entered the hall through the main entrance and opened fire onto the concertgoers, who then tried to flee through the emergency exit, where a third gunman was waiting.

Another detail from the report shows how the Islamic State's members have refined their techniques. Hostages told the police that the terrorists tried to use their phones to access the internet (there was no data reception though) rather than calling and sending messages, which can be tracked by the police.

The report says no electronic communication or emails were found by investigators, leading the police to conclude that the terrorists used encrypted means of messaging, though investigators do not know what kind.

French special forces evacuating people near the Bataclan concert hall after fatal shootings in Paris on November 13. Christian Hartmann/Reuters The attackers used disposable phones, which they left behind everywhere they went, including some used only very shortly before the attacks. Records showed that many calls made from the discarded devices were made to Belgium, where Abdeslam fled to and was eventually captured.

According to witness statements, at some point during the hostage taking at the Bataclan, one of the gunmen who was wearing an explosive belt and holding a detonator in his hand, reportedly started playing the xylophone while laughing "sadistically." He was the first attacker shot by the police; when he was wounded, he blew himself up.

The report said it took four elite brigades to stop the gunmen.

As of this weekend, 18 people have already been detained on suspicion of aiding the Paris attackers. Abdeslam is thought to be the last person alive to have been directly involved with the attacks, but France, Belgium, and Europe remain on high alert.

At the news conference announcing the capture of Abdeslam, French President François Hollande was very cautious not to let news of the capture be associated with any sense of finality, saying the operation "was not a conclusion" and the fight against terrorism in Europe was ongoing.

Read the whole New York Times article here.