The U.K. is preparing to formally blame Russia for the attempted murder of former spy Sergei Skripal with a nerve agent. Fingers were pointed at Russia as details emerged about the attack, which took place last Sunday, but the government has been careful to avoid directly implicating the country. However, The Times of London reported Monday that Prime Minister Theresa May is “on the verge” of publicly blaming Russia for the attack—which left Skripal and his daughter, Yulia, critically ill—and is expected to announce a package of punitive sanctions, including expulsions of diplomats. Government officials told the newspaper that police and security services had now gathered sufficient evidence to be able to blame Moscow, and that an announcement could come Monday after a meeting of the U.K. National Security Council. In Salisbury, where the attack took place, new evidence emerged that led to police warning as many as 500 people to wash any clothes and possessions they had on them on the day of the attack or risk being contaminated.