LONDON, July 19, 2018 (News Wires) - British police have identified several Russians who they believe were behind the nerve agent attack on former double agent Sergei Skripal and his daughter, the Press Association reported on Thursday, citing a source close to the investigation. Skripal, a former colonel in Russian military intelligence who betrayed dozens of agents to Britain's MI6 foreign spy service, and his daughter Yulia, were found unconscious on a public bench in the British city of Salisbury on March 4. Britain blamed Russia for the poisonings and identified the poison as Novichok, a deadly group of nerve agents developed by the Soviet military in the 1970s and 1980s. Russia has repeatedly denied any involvement in the attack. After analyzing closed-circuit television, police think several Russians were involved in the attack on the Skripals, who spent weeks in hospital before being spirited to a secret location, Press Association reported. "Investigators believe they have identified the suspected perpetrators of the Novichok attack," the unidentified source close to the investigation said, according to PA. "They (the investigators) are sure they (the suspects) are Russian," said the source, adding security camera images had been cross checked with records of people who entered the country. The motive for attacking Skripal, an aged Russian traitor who was exchanged in a Kremlin-approved spy swap in 2010, is still unclear, as is the motive for using of an exotic nerve agent which has such overt links to Russia's Soviet past. A British woman, Dawn Sturgess, died this month after coming across a small bottle containing Novichok near the city of Salisbury where the Skripals were struck down. Her partner, Charlie Rowley, is still in hospital. A British police officer was also injured by Novichok while attending to the Skripals in March.