French police investigating the murder of a priest in Normandy are trying to identify members of a closed channel on the messaging app Telegram where one of the attackers outlined his murder plan.
As Muslim worshippers joined Christians in services across France on Sunday in a show of homage to Father Jacques Hamel, 85, murdered on Tuesday in a Normandy church, police said establishing connections between suspects was “like trying to untangle a ball of wool”.
Detectives are seeking to establish how killers Adel Kermiche and Abdel Malik Nabil Petitjean, both aged 19, first came into contact and if an intermediary introduced them. The two met for the first time three days before their attack on Tuesday, in which they took six hostages and cut Hamel’s throat.
At the centre of the investigation is the encrypted message app Telegram, on which Kermiche was part of a closed forum of 200 people. The French news magazine L’Express reported that he posted an audio message on 19 July, a week before the attack, saying: “You take a knife, you go in a church, you cause carnage … you cut two or three heads and there you are, it’s done.”
On Sunday, one of Petitjean’s cousins appeared before an anti-terrorist judge and is expected to be officially put under investigation in connection with the attack on the church at St-Étienne-du-Rouvray, near Rouen in Normandy. The suspect “was fully aware of his cousin’s imminent violent action, even if he did not know the precise place or day,” the Paris prosecutor said in a statement.
A Syrian refugee taken in for questioning after a photocopy of his passport was found at Kermiche’s house was released.
Muslims attended Catholic masses around France on Sunday after the French Muslim council called for a show of “solidarity and compassion” after Hamel’s murder.
“The death of Father Hamel has given us a responsibility and a historic duty to continue his work in peace,” Otmane Aissaoui, imam of the Ar-Rahma mosque in Nice, told Agence France-Presse.
At Rouen Cathedral, packed with around 2,000 people, the archbishop, Monsignor Dominique Lebrun, addressed a congregation that included local Muslims and three nuns who were at the church in St-Étienne-du-Rouvray when Hamel was murdered.
“Our world has proven united from one side of the planet to the other,” he told them. “Injustices between people have become intolerable. Faced with the horrible and unjust death of a simple priest, messages have come from around the world. Hope is on the march,” he said.
Kermiche was imprisoned between 22 May 2015 and 22 March 2016 in the high-security Fleury-Mérogis prison outside Paris while awaiting trial for trying to travel to Syria. He was released on 22 March on conditional bail with an electronic bracelet.
L’Express said that in his Telegram messages, Kermiche had claimed he had been influenced and “given ideas” by a “sheikh” he met in prison and wanted to create a terrorist cell, giving details of his failed attempts to reach the ranks of Islamic State in Syria.
In other messages, Kermiche said he would show “brothers” who mocked him for being an “armchair jihadi”.
At 8.30am on 26 July, the day of the attack, Kermiche left his last message on the app: “Download what is about to happen and share it en masse!!!!!!” he wrote.
Kermiche and Petitjean were shot dead by police as they left the Sainte Thérèse church after the attack. Both had pledged allegiance to Isis in a video made before the attack.
Detectives have yet to establish how Kermiche and Petitjean, from Aix-les-Bains in the Savoie region on the other side of France, had made contact.
Petitjean, who had a professional diploma in sales, had shown no sign of religious conviction until three months ago. He was cleared by security checks in December 2015 to work as a baggage handler at nearby Chambéry airport until April 2016. His radicalisation is believed to have taken place in the first three months of this year.
His stepfather, Franck, told Sud-Ouest newspaper that Petitjean’s mother, Yamina, had been summoned by the imam at the local mosque at Aix-les-Bains and told her son was “hanging out” with religious extremists.
France’s interior ministry has asked local security services to make plans for the protection of all places of worship in the run-up to 15 August, Assumption day. The French prime minister, Manuel Valls, says he is considering a ban on foreign-funded mosques in France.
Father Hamel’s funeral will be held at Rouen Cathedral on Tuesday.