Last Friday, FBI Director James Comey drew praise and condemnation alike for a letter he sent to Congress informing them he was revisiting the matter of Hillary Clinton's private email server.

Among Republicans pushing for Donald Trump to win in November, Comey's decision was a rectification of his previous leniency on Clinton back in July, when he decided not to press charges. Democrats saw it as an overtly political attempt to sway the election.

Homeland security expert Juliette Kayyem, author of "Security Mom," says that any way you cut it, Comey has made a mistake by stepping into the political crossfire.

"He opened up, in some ways, his own Pandora's Box," said Kayyem.

The big problem, according to Kayyem, is that the story has become about Comey itself—his political leanings, his motives, and his decision-making process—which is anathema to what the role of the FBI Director should play in cases like this.

"The big frustration for me, besides the fact it is having some impact on the polling and the tightening of the polls, is one, you don't do this anyway and there are rules against it, and also the idea that it's all about Comey," Kayyem said.

"The whole point of being the FBI Director is it's not about you. It's not about what you promise Congress or whether you have some moral authority, or your word to Congress. There are reasons why there are established rules to guide prosecutors, directors, and attorneys general and whatever else regarding elections. You're not the judge of that."

By releasing his letter so close to Election Day, Comey has compromised the impartial nature of his office—and that's dangerous, Kayyem said.

"He's made leadership mistake 101: he made it personal," Kayyem said.

To hear more from Juliette Kayyem, tune in to Boston Public Radio above.