The FBI has expanded its probe into Hillary Clinton’s personal email system to what one analyst is calling a “full-blown investigation,” Politico is reporting.

The FBI has interviewed a former State Department official about how Clinton aides communicated over email. And last month, the agency requested records from a data broker Clinton hired to find companies to manage her private email system after she left office in early 2013.

While the FBI’s handling of the case has so far been characterized as a “preliminary inquiry,” the depth of the probe indicates it has reached a new phase.

“This sounds to me like it’s more than a preliminary inquiry; it sounds like a full-blown investigation,” Tom Fuentes, a former assistant director of the FBI, told Politico. “When you have this amount of resources going into it…I think it’s at the investigative level.”

The FBI has already taken control of Clinton’s server, which had been kept at a New Jersey data center since 2013. The company that managed the server, Platte River Networks, is reportedly cooperating with the FBI, as is Datto, Inc., a company that was hired to back up the server on the cloud.

Clinton’s attorney, David Kendall, also recently turned over three thumb drives that were in his possession which held all of the emails Clinton turned over to the State Department in December.

As Politico reports, the FBI last month requested documents from Tania Neild. Working as a data broker who puts companies in touch with wealthy customers, she reportedly set up the contract between Clinton and Platte River Networks. Neild confirmed to Politico that the FBI has asked her for records related to her work for Clinton.

The FBI has also interviewed a former high-ranking State Department policy official about Clinton’s emails. The agency asked the official whether anyone at the State Department was concerned about the handling of classified information on Clinton’s email system. The official told Politico that they were not aware of such concerns.

As secretary of state, Clinton sent and received emails hundreds of emails that the State Department has retroactively deemed to be classified. While many of the emails center on topics that were time- and event-specific, the State Department insists that the information was not classified at the time of origin.

Two other emails that were forwarded to Clinton on her unsecured email account contained “top secret” information, the Intelligence Community’s inspector general determined. The discovery of those emails is what reportedly prompted the FBI to seize Clinton’s server and open up its inquiry.