Parallel lives: the Brussels suspect and the Toulouse shooter

The Toulouse killings were carried out by Mohamed Merah, a French citizen of Algerian descent who was inspired by al Qaeda.

While there is no indication that the two men knew each other, they come from similar backgrounds. Both are French Muslims who came from broken homes and both were apparently radicalised in prison before going overseas to wage jihad.

They were both also keen to film their crimes. Paris prosecutor François Molins told reporters on Sunday that 29-year-old Nemmouche, still being questioned for allegedly killing four people in Brussels last week, had a Nikon camera in his possession as well as video recordings in which he discussed his actions.

Molins said the "repeat offender" explained in the film that he had attached a GoPro camera to his bag to record his shooting rampage, but it had not worked.

Instead Nemmouche later "filmed his weapons and said he carried out the attack against the Jews in Brussels", according to Belgian prosecutor Frederic Van Leeuw.

In 2012, Mohamed Merah filmed the killings of one French soldier in Toulouse, two paratroopers in nearby Montauban and the murder of Jewish children and a teacher at a school in Toulouse.

He sent the video to Qatari news channel Al Jazeera, but the broadcaster rejected any use of the violent footage.

Both men known to intelligence services and police

Another link is that both men had already been identified as potential threats by France’s DGSI domestic intelligence agency. In 2012 the DGSI came under heavy criticism for failing to stop Merah during his killing spree. Two years later, it seems that history is repeating itself.

Nemmouche returned from fighting in Syria via Malaysia, Singapore and Bangkok. On March 18 he was questioned by German border police and his return was pointed out to the DGSI.

They lost track of him until he was discovered during a routine drugs search in Marseille – he was travelling on a bus from Amsterdam – a whole week after the killings in Brussels.

Molins said the suspect, from the northern city of Roubaix, had a revolver and a retractable automatic weapon like those used in the Brussels attack, and ballistics analyses were underway to determine if they were the same weapons.

Unhappy childhoods, prison and a call to arms

Both men endured difficult childhoods. Merah's parents split up at the age of four. His mother was unable to look after him and he was taken into care.

Nemmouche had a similarly unhappy childhood. He never knew his father and was adopted at the age of three after his mother was considered incapable of looking after him.

According to his former lawyer Soulifa Badaoui, he was “shunted from one foster home to another” until he went to live with his grandmother at the age of 17.

Both men drifted into petty crime as adolescents. By the age of 17, Merah was well known to the police in his home town of Toulouse. He was jailed twice between 2007 and 2009, by which time he was 21 years old, and it was in prison that he discovered radical Islam.

Nemmouche was also known to the police.  Between 2004 and 2009, he was convicted seven times for attempted robbery, driving without a license and refusing to answer police questions.  He spent repeated spells in prison where he too discovered radical Islam.

On their release, both men made their way to overseas conflicts as ardent jihadists. Merah headed to Afghanistan and Pakistan, while Nemmouche joined the Islamic State of Iraq and the Levant, a group fighting in Syria and linked to al Qaeda, just three weeks after leaving prison.

“You can compare these men in the sense that they're both 'lone wolves’,” said Molins. “They both entered war zones, took part in combat and became versed in the use of weapons.”