Yahoo said investigators were looking into the possibility that some people within the company knew at the time about the late 2014 theft of information of at least 500 million user accounts.

Law enforcement authorities on Monday also “began sharing certain data that they indicated was provided by a hacker who claimed the information was Yahoo user account data,” the company said in a regulatory filing to the U.S. Securities and Exchange Commission. Yahoo said it would “analyze and investigate the hacker’s claim.” It isn’t clear if this data is from the 2014 hack or from another breach.