Investigators have come across several connections between the attackers who killed 130 people in Paris last November and the perpetrators behind suicide bomb attacks in Brussels last month that left 32 people dead.
Here are some of the links that have emerged:
MOHAMED ABRINI: Investigators had been after the 31-year-old for months due to his links to the Paris terrorist attacks, when he was arrested in Brussels on Friday. The following day, he confessed to being the fugitive third attacker at the Brussels airport, known as the "man with the hat" based on video surveillance images. He is thought to have left explosives at the airport, where two others set off suicide bombs.
Abrini was seen alongside SALAH ABDESLAM in the days before the Paris attacks and rented an apartment with him that was used by the Paris perpetrators. But his family says he was in Brussels on the night of the attacks.
SALAH ABDESLAM: The 26-year-old French national was Belgium's most wanted man up until his arrest in the Brussels neighbourhood of Molenbeek in March. He is now in Belgian custody, awaiting extradition to France.
Investigators have found that Abdeslam travelled with several of the perpetrators from Belgium to Paris, where his brother BRAHIM and six others died while carrying out the November attacks. Salah is believed to have driven several perpetrators to the Stade de France sports stadium, later leaving the car in a Paris neighbourhood. He discarded a suicide belt in a suburb outside the city. It is unclear why he did not blow himself up. A family member said following a prison visit that he had wanted to avoid further bloodshed.
Abdeslam is said to have later left fingerprints on a glass in the apartment rented by KHALID EL BAKRAOUI in the Brussels neighbourhood of Forest. Four days after Abdeslam's arrest, the 27-year-old blew himself up in a Brussels underground carriage, while his brother IBRAHIM EL BAKRAOUI set off one of the airport bombs.
NAJIM LAACHRAOUI: The electrical engineer from the Brussels neighbourood of Schaerbeek is believed to have made the bombs used in the Paris attacks. Traces of his DNA are reported to have been found among explosive material. The 24-year-old was the second Brussels airport suicide bomber. He is believed to have been one of the first Belgian jihadists to join the Islamic State extremist group in Syria, in 2013.
Laachraoui was travelling under the false name of SOUFIANE KAYAL when he was controlled on a journey from Hungary to Austria last September - together with SALAH ABDESLAM and MOHAMED BELKAID. The latter died during a police raid on the apartment in Forest in March, and in the days after the Paris attack a money transfer was carried out under a false identity of his to the cousin of the alleged attack mastermind, ABDELHAMID ABAAOUD.
IBRAHIM EL BAKRAOUI: The 29-year-old was convicted for violent crime and sentenced to 10 years in prison in 2010 but released on parole in 2014. In mid-2015, he was stopped on the Turkish-Syrian border and deported to the Netherlands. He blew himself up at the Brussels airport with NAJIM LAACHRAOUI.
KHALID EL BAKRAOUI: The younger brother of IBRAHIM EL BAKRAOUI, who blew himself up in the Brussels metro, used aliases to rent the apartment in Forest and a house in the Belgian city of Charleroi, where the Paris attackers are believed to have been before the attacks.
ABDELHAMID ABAAOUD: The Greek broadcaster Skai reported that the alleged mastermind of the Paris attacks rented an apartment in Atehns in which police found plans in 2015 for an attack on the Brussels airport. The 28-year-old Belgian was one of the men who attacked several bars in eastern Paris.
He died days later in a raid on an apartment in the Paris suburb of Sait-Denis, along with the ninth Paris attacker. They are believed to have prepared another attack on the Paris business area of La Defence. Abaaoud's name has been linked to several terrorist suspects.