LONDON — A group of investigative journalists from Britain and Russia on Wednesday named a highly decorated colonel in Russia’s military intelligence service as one of the men accused of poisoning a former Russian spy and his daughter in Britain earlier this year.

A report by the investigative group Bellingcat and the Insider, a Russian news outlet, named the suspect as Col. Anatoly V. Chepiga, a 2014 recipient of the title Hero of the Russian Federation, probably for service in eastern Ukraine. The award, given to only a handful of officers each year, is typically bestowed personally by President Vladimir V. Putin, the report said.

The police in Britain would not comment on the report, and Russia also offered no response.

Moscow has denied any involvement in the attack on the former spy, Sergei V. Skripal, who was living in the English city of Salisbury after being released from a Russian prison in a spy swap.

The two men Britain identified as the prime suspects have told the Russian news media that they were merely sports nutritionists who had visited Salisbury to see the sights and scout for new nutrition products.

But the report by the Insider and Bellingcat — a group that has also carried out research on the conflicts in Syria and Ukraine — appears to support Britain’s assertion that Moscow was behind the poisoning.

The journalists provided a detailed account of their methodology in identifying Colonel Chepiga as one of the suspects.

After the British authorities released security camera images of the two main suspects this month, reporters from Bellingcat and the Insider set about trying to learn their identities. The British authorities named the men as Alexander Petrov and Ruslan Boshirov, based on their Russian passports, but officials suggested that these were aliases.

Mr. Boshirov, the new report says, is actually Colonel Chepiga.

The reporters began by searching through yearbooks for Russia’s Far Eastern Military Command Academy, which frequently prepares officers for overseas clandestine operations.

Identifying Colonel Chepiga in a photograph of officers deployed in Chechnya, they then scoured databases, social networks and the internet, but discovered little trace of him aside from a 2003 passport photograph. A passport application from that period gave his place of residence as a military unit based in Khabarovsk, but then there were few records of his existence until 2014, when his military school boasted on its website of his winning the Hero of Russia award.

That honor is typically awarded in a public ceremony and accompanied by a presidential decree, except in cases where the underlying act is part of a secret mission. While there is no reference to Colonel Chepiga’s award on the Kremlin website, a website dedicated to the graduates of the Far Eastern Military Command Academy says he received it for “conducting a peacekeeping mission.”

Earlier this month, the British authorities released security camera images of two men traveling from an Aeroflot flight to the scene of the poisoning, near the victim’s home, and from there back to Moscow. Investigators also said traces of the nerve agent Novichok, which was used in the attack, had been found in the hotel room where the two men stayed.

Several days later, the two suspects appeared on an interview with RT, a Russian state-funded network, saying that they had no connection to the attack on Mr. Skripal. They said, instead, that they were tourists who had traveled to the “wonderful” English city of Salisbury to see its cathedral spire and 14th-century clock.

Britain’s Crown Prosecution Service has charged the men with the attempted murder of Mr. Skripal; his daughter, Yulia S. Skripal; and a police officer, Det. Sgt. Nick Bailey, who was sickened while investigating the case. The men were also charged with conspiracy to murder Mr. Skripal; use and possession of the nerve agent; and causing grievous bodily harm. The authorities issued domestic and European arrest warrants for the two men.

Prime Minister Theresa May, citing British intelligence, said the suspects were officers in a branch of Russia’s military intelligence known as the G.R.U., the same group accused of disrupting the 2016 United States presidential election.

Mrs. May also said that the Salisbury attack “was almost certainly also approved outside the G.R.U. at a senior level of the Russian state.”

Russia imprisoned Mr. Skripal in 2004 for selling secrets to Britain, and released him in 2010 as part of a spy swap with Western countries. He settled in Salisbury but continued working in intelligence, offering insights into Russian espionage practices.

The Skripals fell seriously ill on March 4 with what was diagnosed as nerve agent poisoning, leading to a lockdown of parts of Salisbury. Residents were terrified as hundreds of workers in hazardous materials suits searched for contamination.

Doctors did not expect them to survive, but the Skripals, who were found unresponsive in a Salisbury park, were released from a hospital after weeks of treatment.

Months later, two Britons, Dawn Sturgess and Charlie Rowley, fell ill after being exposed to the poison. Ms. Sturgess died.

After the attack on the Skripals, Western nations imposed new economic sanctions on Russia and expelled about 150 Russian diplomats and other officials, many of them believed to be intelligence agents. Russia responded by ejecting a similar number of officials from those countries.

On Wednesday at the United Nations General Assembly, Russia’s foreign minister, Sergey V. Lavrov, said Britain had given no proof of Russia’s guilt in the poisoning.

ELLEN BARRY