One of alleged assassins sent by the Kremlin to poison a former Russian spy in England is a military doctor for Russian military intelligence, according to online investigative news outlet Bellingcat.

British authorities named “Alexander Petrov” as one of two assassins sent to murder Main Intelligence Directorate (GRU) defector Sergei Skripal in March after discovering security camera footage of him and another man, “Ruslan Boshirov,” in Salisbury at the time. Prime Minister Theresa May claimed that Skripal and Boshirov were both GRU assassins traveling under fake identities, but the two men claimed on Russian state television that they were merely sightseeing on a business trip.

Using open sources and a copy of a scanned passport, the investigative news outlet Bellingcat has identified the second alleged assassin,“ Petrov,” as Alexander Mishkin and claims that he is a GRU physician. Mishkin reportedly obtained his cover as “Alexander Petrov.” using the same name and birthdate, in 2010 and made several trips to Ukraine through 2013. An address listed for Mishkin in September 2014 was nearby Khoroshevskoe Shosse 76B—is the same at the intelligence agency’s Moscow offices.

Bellingcat, alongside Russian news outlet, The Insider, previously identified “Ruslan Boshirov,” Petrov’s travel partner in Salisbury, as GRU Colonel Anatoly Chepiga using similar passport data as well as images from social media. Bellingcat searched through open source records posted on the Internet by Russian military academies known to train GRU officers. Photographs from Russia’s Far East Military discovered by Bellingcat reveal a portrait of Anatoliy Chepiga hanging on a wall of honor reserved for recipients of the Russian military’s prestigious “Hero of the Russian Federation” award. Records show that Chepiga was a veteran of Russia’s 14th Spetsnaz Brigade who had fought in Chechnya and Ukraine.

Following Bellingcat’s revelation of Chepiga’s identity, a host of news organization spoke with residents of his hometown and associates of his family who confirmed that the “Boshirov” they saw on TV was, in fact, Anatoliy Chepiga. “It’s true. He’s our guy,” one family friend told The Washington Post . Other associates confirmed Chepiga’s identity to the BBC and Daily Telegraph.

British officials say Skirpal and his daughter, Yulia, were poisoned with a class of top secret nerve agent, Novichok, disguised inside a perfume bottle by the alleged GRU assassins and smeared on a door handle at Skripal’s Salisbury home. Former scientists who helped the Soviet Union develop Novichoks in secret in the waning years of the Cold War revealed the existence of the weapons in the early 1990s, but Russia denies ever developing the nerve agent.

The Russian government has denied any involvement in the poisoning of Skripal, a GRU officer recruited by British intelligence in the 1990s, arrested by Russia in 2004 and subsequently released to the U.K. as part of a spy swap between the U.S and Russia in 2010. Nonetheless, Moscow has not concealed its anger at its former spy. Russia President Vladimir Putin blasted Skripal to reporters last week during an appearance at an energy forum. Skripal, Putin said, was a “traitor to the motherland” and “simply a scumbag.”