The FBI announced on Monday that it has formally opened an investigation into the hack of the Democratic National Committee.

Specifically, the FBI said it is looking into figuring out “the nature and scope” of the hack, while also noting that “a compromise of this nature is something we take very seriously.”

Democratic Party officials have said that they suspect Russian intelligence agencies are behind the hack in an effort to boost the election prospects of Donald Trump. While there has been a lot of circumstantial evidence to suggest Russian involvement, there has been no definitive evidence put out yet.

This past weekend, WikiLeaks published thousands of DNC emails that embarrassed party officials and caused DNC Chairwoman Debbie Wasserman Schultz to announce that she would be stepping down from her role after the convention.

Among other things, the emails show that some DNC staffers floated the idea of questioning Bernie Sanders’s religious faith and that Wasserman Schultz referred to Sanders campaign manager Jeff Weaver as a “damn liar.”