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", The Guardian reported.

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 a 30-year-old cousin of Petitjean’s was placed in preventive detention, the Paris prosecutor’s office said. The man, born in Nancy, identified as Farid K, was put under formal investigation on suspicion of terrorist association with a view to perpetrating a crime, the prosecutor’s office said.

Another man, named as Jean-Philippe Steven J, 20, was also put under formal investigation for attempting to travel to Syria in June with Petitjean. He was also sent to preventive detention.

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.

Source: MENA