The U.S. Department of Justice has granted immunity to Hilary Clinton’s aide Bryan Pagliano, who helped set up her privately maintained email server. Former federal prosecutors, both Republicans and Democrats, said the immunity deal is a serious step in the FBI’s investigation.

However, an immunity deal doesn’t necessarily mean anyone will get indicted.

“Sometimes, I, as a prosecutor, would give immunity even when I wasn’t planning to prosecute that person, just to get more information about what happened,” Henry E. Hockeimer, another former federal prosecutor who has worked on public corruption cases told LawNewz, “What this guy has to say may dictate whether this inquiry moves forward.”