Detectives believe Jean-Baptiste Salvaing (below) was killed first and then his wife Jessica Schneider (above) and the boy witnessed both killings.
An ISIS militant murdered a police commander and his wife at their home near Paris before being shot dead by officers who rescued the couple's three-year-old boy unharmed.
After killing the couple Larossi Abballa, 25, recorded a 12 minute monologue to camera while in the couple's house in Magnanville and posted the video on Facebook Live.
In the video, Abballa says: 'We will come and find you the way I have found this policemen at his house.'
He also hinted at an ISIS attack on the Euro 2016 football tournament, saying: ‘We're keeping another surprise for the Euros but I won’t say anything more.'
And, chillingly, he also hinted that the son of his victims was also in danger, saying: 'I don't know what I'm going to do with the boy.'
[. . .]
Police later raided Abballa's home and found a hit list on his computer which contained six names.
Prosecutor Francois Molins said they included 'rappers, journalists, police officers and public personalities'.
During Abballa's video diatribe he expressed particular hatred for journalists Bernard de La Villardière, Audrey Pulvar, Mohamed Sifaoui and Lea Salame, political scientist Gilles Kepel and rapper Booba.
Booba is of Senegalese Muslim origin and was, ironically, accused of anti-Semitism in 2014 for the lyrics of a song which appeared to praise Mohammed Merah, a lone wolf who killed seven people, including a rabbi and three Jewish children in Toulouse in 2012.
Abballa called on Muslims to kill journalists and police officers and added: ‘Target their fear.’
He stabbed Jean-Baptiste Salvaing, 42, nine times in the stomach at his home in the Yvelines department, north west of Paris, shortly after 8.30pm on Monday.
After a three-hour stand-off elite Raid commandos entered the building, where they killed Abballa.
Inside the house, they found the lifeless body of Mr Salvaing's wife, Jessica Schneider, who was an administrator who worked for the police force in Mantes-la-Jolie.
The only survivor was the couple's three-year-old son, who was 'extremely shocked but otherwise unharmed'.
[. . .]
The couple's young son was 'in shock but unharmed,' a prosecutor added, saying he was receiving medical attention.
Mr Molins said Abballa pledged his allegiance to ISIS three weeks ago and appeared to be following a recent order from ISIS leader Abu Bakr al-Baghdadi 'to kill miscreants at home with their families' during Ramadan.
Three men - 'linked to' Abballa - were arrested on Tuesday morning. They were described as 'acquaintances' and are aged 27, 29 and 44.
It also emerged today the knifeman was part of a recent investigation into a Syrian jihadist network.
French security expert David Thomson said Abballa posted gruesome images of the murdered couple on the internet.
A French flag flies half-mast outside the police station in Les Mureaux, where a French police commander who was killed in nearby Magnanville, worked.
Abballa's Facebook profile, under the name Mohamed Ali, was suspended in the early hours of this morning.
Mr Thomson told a Paris radio station that at one point Abballa could be seen sitting on the sofa with the child behind him.
Abballa wrote: 'I still don't know what I'm going to do with him.'
Abballa had also been sentenced in 2013 for taking part in a jihadist organisation with links to Pakistan.
He was sentenced to three years behind bars, six months of which were suspended for 'criminal association with the aim of preparing terrorist acts' following a trial with seven other defendants.
Despite this, he only spent a few months in prison, and is thought to have maintained his links with a group sending jihadists to fight in Afghanistan.
It has also been revealed Abballa had previously claimed allegiance to ISIS and sources say he did so again while talking to officers during the siege.
The terror group's al-Amaq news agency said the attacker was an 'Islamic State fighter' and claimed responsibility for the
Attacker who pledged allegiance to ISIS murdered police commander and his wife at their home near Paris before being shot dead by officers in raid that saw child hostage rescued
Jean-Baptiste Salvaing, 42, knifed to death outside his home in Magnanville, northwest Paris
Police raided home after Larossi Abballa, 25, took officer's family hostage
Inside, they found the body of the commander's wife but child was rescued
Witnesses say Aballa may have shouted 'Allahu akbar' as he knifed victim
Hours later the Islamic State group claimed responsibility for the murders
Abballa sentenced in 2013 for taking part in a jihadist organisation
By PETER ALLEN IN PARIS and JULIAN ROBINSON FOR MAILONLINE
PUBLISHED: 17:06 EST, 13 June 2016 | UPDATED: 01:02 EST, 14 June 2016