Last week, the investigative group said it "can confirm definitively" that the two suspects have links to the GRU, "based on objective data and on discussions with confidential Russian sources familiar with the identity of at least one of the two persons", and said the men's names were believed to be aliases.
It added: "Based on the array of information sources consulted - all of which were independent from each other and came from different time periods - Bellingcat was able to conclude with certainty that the person identified by United Kingdom authorities as "Ruslan Boshirov" is in fact Colonel Anatoliy Vladimirovich Chepiga, a highly decorated senior officer from Russian military intelligence who was awarded the highest state honour in late 2014".
Former Russian military intelligence colonel Sergei Skripal attends a hearing at the Moscow District Military Court in Moscow on August 9, 2006.
The colonel was in 2014 awarded Russia's highest medal, the Hero of Russian Federation.
The two suspects have insisted they were on holiday in Salisbury and had no connection with the attack.
In its report about Colonel Anatoliy Chepiga, Bellingcat outlines how its investigation arrived at its conclusion.More news: Seth Meyers On Rod Rosenstein: 'Don't Make Jokes! Jokes Are Broken Now!'
One of the suspects has been identified as Anatoliy Chepiga.
After Scotland Yard took the extraordinary measure to publicly identify the pair earlier this month, the men appeared on Russia TV claiming to work in the fitness industry and having wanted to visit Salisbury for its "wonderful" sites.
It's understood counter-terrorism police and security services know Petrov's real name.
He then served in the special forces of the GRU. Other Russian soldiers who have recently received the award with few details mentioned have been found to be fighting covertly in eastern Ukraine or Syria.
The men were seen in Salisbury on the day of the attack, 4 March, according to CCTV footage.
In response to the Skripal poisoning, U.S. Ambassador to the U.K. Woody Johnson said in a tweet earlier this month that the U.S. and Britain "stand firmly together in holding Russian Federation accountable for its act of aggression". Sergei Skripal's daughter Yulia Skripal seen in this undated photo. Rowley survived but Sturgess died from her contact with the poison. This award is bestowed personally by the President of Russian Federation "as recognition of services to the state and the people of Russian Federation involving a heroic deed". Russia's foreign ministry has previously denounced Bellingcat, alleging the group is related to Western intelligence agencies.