Paris attackers -- what we know so far

French police made another arrest Tuesday in connection with the Paris attacks, which left 130 people dead, as the international manhunt for two suspects went on.

Here is a summary of the latest developments in the investigation.

- Two key suspects on the run -

Mystery surrounds the fate of key suspect Salah Abdeslam, the 26-year-old brother of one of the suicide bombers in the Paris attacks, who investigators think played a vital logistical role and may have been supposed to blow himself up as well.

CNN on Monday said Abdeslam, who is Belgian, had managed to slip out of Europe and into Syria since the November 13 atrocity, though investigators believe he may still be in Europe.

"At this stage, no one knows where he is. His departure to Syria is just one of the hypotheses that investigators are working with," a French police source told AFP.

Belgian investigators are meanwhile working on the assumption that Abdeslam is still in Belgium, where he is believed to have fled to hours after the Paris attacks.

Also on the run is Mohamed Abrini, a 30-year-old Belgian-Moroccan who also faces an international arrest warrant.

He was seen in surveillance footage with Abdeslam at a petrol station north of Paris two days before the attacks, driving one of the vehicles that were used in the assault -- the deadliest of its kind in French history.

- Fresh arrest -

Six anti-terror judges who have been leading the French probe since November 24 are also going after possible accomplices of the jihadists behind the attack.

Four of eight suicide bombers have yet to be identified -- including one who blew himself up during a police raid on November 18 on a flat in the Paris suburb of Saint-Denis.

Police on Tuesday arrested near Paris a relative of Jawad Bendaoud, who lent the apartment to Abdelhamid Abaaoud, the suspected ringleader of the attackers. Abaaoud was killed in the Saint-Denis police raid.

Jailed since Friday, Bendaoud is the only person to have been charged in France in relation to the attacks.

In Belgium meanwhile, six suspects have been charged with terrorism offences in connection to the attacks, including three men accused of helping Abdeslam escape after the carnage.

- The mystery of Abaaoud -

Abaaoud, who was under an international arrest warrant, was thought to have been in Syria -- where he had boasted of planning attacks on the West.

No one knows how long he had been back in Europe before last month's attacks. His mobile phone was tracked in Greece in January, and a non-European intelligence service told France after the attacks that the wanted jihadist had arrived in Greece in September.

Questions remain over whether he used a fake passport to travel back into Europe or whether he infiltrated the migrant route. Greece has denied France's claim that Abaaoud had been in the country.

Investigators nonetheless say it would have been very difficult for him to hide for a whole two months in Belgium, where he is very well known.

The way he was found and killed in France also appears to suggest he did not have a network solid enough to get him out alive.

It is also unclear whether Abaaoud was planning any other attacks, and whether he was stopped in his tracks before it was too late.