The Russian government has denied responsibility for the killing of a Chechen exile in Berlin after German authorities reportedly voiced suspicions of a state-backed attack similar to that carried out against a former Russian military officer in Salisbury, Britain, in 2018.

Zelimkhan Khangoshvili, who fought against Russia during the second Chechen war in the early 2000s, was shot twice in the head at close range in the Kleiner Tiergarten park in central Berlin just before midday last Friday.

Associates of Khangoshvili said he commanded a fighting unit against Russian troops between 1999 and 2004. After the end of the conflict, Khangoshvili moved back to Georgia where he was employed as a mediator by the anti-terror unit of the Georgian interior ministry. He continued to help the Chechen insurgency and continued to be regarded as a terrorist by Russia’s intelligence agency, the FSB.

From his base in Georgia, Khangoshvili helped to send supplies over the mountains into Chechnya and to evacuate wounded fighters, his associates said. However, they insisted he was not a radical or an Islamist. “He was always against Chechens going to fight in Syria or Afghanistan; he thought our only battle was with Russia,” said Saikhan Muzayev, who knew Khangoshvili from Georgia and saw him in Berlin three months ago.

A suspect named in the German media as Vadim S was arrested by Berlin police before he could leave the scene of the crime on an electric scooter parked in a nearby bush.

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Two 17-year-olds had reportedly seen the man throwing a Glock handgun with a silencer, a bicycle and a wig into the river Spree and alerted the authorities.

Ekkehard Maaß, a former East German dissident songwriter who now chairs the German-Caucasian Society, said he had met Khangoshvili when he first arrived in Germany at the end of 2016 and had personally appealed to the authorities in January 2017 to grant him special protection.

Khangoshvili arrived in Germany after six months in Ukraine, having fled Georgia after surviving two assassination attempts there, one by poison in 2009 and one where he was shot at eight times while driving his car in central Tbilisi in May 2015, said Maaß.

“Zelimkhan thought that now he was in Germany he would be safe, and every Friday he took the same route from his home to the mosque. He must have been noticed, and the information passed to the killer,” said Maaß.

Khangoshvili, who lived in Berlin under a pseudonym, had three daughters and two sons aged between two and 17. A small memorial was held in Berlin on Tuesday before his body was flown back to Georgia.

Muzayev, who attended the ceremony and took part in the Chechen ritual of washing the body before the funeral, said he saw one bullet wound in the shoulder and two in the head. “He was shot in the shoulder and fell to the ground, and then he was finished off,” he said.

When he was caught by the police, the alleged assassin, a 49-year-old Russian citizen from Siberia, had changed his outfit to blend in as a tourist, wearing a pink shirt, sandals and a neck pouch containing a passport and a large amount of cash.

A rucksack that police recovered from the river contained a shaving kit and paprika powder, which can be used to throw sniffer dogs off a scent.

Vadim S, who had only arrived in Berlin a few days before the killing, has denied responsibility for the killing and reportedly refused to answer questions. According to Bild, the suspect requested to speak to a representative of the Russian embassy.

Facebook Twitter Pinterest The Kremlin-backed head of the Chechen Republic, Ramzan Kadyrov. Photograph: Said Tsarnayev/Reuters

On Wednesday the Kremlin denied any involvement in the killing, which took place on the same day that Germany’s foreign minister was visiting Moscow. “I categorically reject any link between this incident, this murder and official Russia,” said Vladimir Putin’s spokesman, Dmitry Peskov.

There have been numerous contract killings of Chechens across the world in recent years, with the victims usually falling into one of two categories: personal enemies of the region’s Kremlin-backed leader, Ramzan Kadyrov, or figures believed to be involved in an insurgency against Kadyrov’s forces and Russian troops in the region.

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In the former set of cases, Chechen murder squads linked to Kadyrov have appeared to be the most likely perpetrators, while the latter hits have borne the hallmark of the Russian federal security services. There have been a number of murders in Istanbul, one of which in 2009 used a Groza pistol, developed for Russian special forces and rarely found on the open market.

While Chechens have been shot with impunity in Istanbul, Dubai and Moscow, it is rare for such killings to take place in broad daylight in western Europe. The closest parallel to Khangoshvili’s killing is the murder of Umar Israilov in 2009, who was shot dead as he left a supermarket in Vienna. Israilov, a former Kadyrov bodyguard, had fled the republic and made allegations of torture against Chechen forces and Kadyrov personally.

Last year the former Russian military officer Sergei Skripal and his daughter were poisoned in Salisbury. Police identified two Russians as the suspects.

Citing unnamed sources, Der Spiegel said German security agencies were increasingly confident Russia’s signature could be detected behind Khangoshvili’s killing. “If it turns out that a state player like Russia is behind this, we have a second Skripal case on our hands, with everything that entails,” the magazine quoted one source as saying.

Maaß said: “I see this as a message to all the Chechen refugees in Germany: you’re not safe here.”