Police have uncovered a large and growing network of Islamic State fighters, at least two of whom came to Europe as “refugees.”

French and Belgian authorities have found that the scale of the threat of terrorism could be much bigger than they had previously thought. They’ve found that the members of these terror cells are mostly young Muslim men from the Brussels suburbs of Molenbeek and Schaerbeek and many were former criminals often involved with petty thefts and assaults.

Among the jihadis is Paris attacker Abdelhamid Abaaoud. Islamic State fighters in Syria gave him the name Abu Omar al-Belgiki meaning that he was Abu Omar from Belgium. Abaaoud lived most of his live in the notorious Brussels suburb of Molenbeek along with many of the other terrorists who took part in the Paris and Brussels attacks.

The 28-year-old terrorist lived and fought for the Islamic State in Syria for at least two years, took part in various battles and sent video messages to sympathizers back home. Abaaoud, also like many ISIS fighters, is said to have committed atrocities toward prisoners such as dragging them behind his pick up truck through the Syrian desert reports Die Welt.

Fighting wasn’t Abaaoud’s major skill, rather he was a skilled recruiter for the Islamic state and was able to create and maintain networks of Islamist fighters, sympathizers and fundraisers. One of his specific skills was recruiting those who wished to become suicide bombers.

Last November in Paris Abdaaoud added himself to the list of those who wished to commit acts of terror when he participated in the Paris attacks that left more than 130 people dead at various locations across the city including the Bataclan nightclub. Many of the attackers in Paris committed suicide and blew themselves up. Abaaoud fled the scene of his crime and hid away with his cousin. He was killed in a police raid five days following the attack.

After the attacks police had a major question: How large was the network that participated in the attacks and were there more sleeper cells in Europe waiting to strike?

The authorities have uncovered a variety of men who have been tied to Abaaoud, either fighting with him in Syria and Iraq or having lived with him at some point. Many of these men are currently being sought by police, but unfortunately police often have no idea if they are in Europe or in Syria.

Two of those wanted by police are 28-year-old Syrian national Naim al-Hamed and his partner Sofia Ayari. Their names are assumed to be aliases as authorities are currently unsure of their true identities. The pair are said to have had a key role in the attacks on both Paris and Brussels. It is thought that they are involved in bomb making or may even be suicide bombers themselves. Both Al-Hamed and Ayari came to Europe on September 20th of last year where they posed as refugees crossing from Turkey to the Greek island of Leros.

They merged into the vast columns of migrants who walked the Balkan route up into central Europe. While in Austria, al-Hamed was able to receive money transfers worth 600 euros, likely from other members of the terrorist cell. The pair were registered in Germany as asylum seekers in October at Feldkirchen in Bavaria after crossing the border.

The day after being registered at the asylum home they appeared in a hotel in Ulm where Salah Abdeslam picked up al-Hamed and Ayari and drove him directly to Belgium. Ayari was later arrested alongside Abdeslam in the raid that preceded the Brussels attacks. Al-Hamed was able to escape and is currently on the run. French police are considering him “armed and dangerous.”