Author and former investigative reporter for The Washington Post and Boston Herald Ron Kessler is backing up assertions first reported by Breitbart News regarding Hillary Clinton from former Secret Service agent Gary Byrne’s forthcoming book Crisis of Character.

Kessler told the Boston Herald, “I think it’s right on. It has to do with her character, the hypocrisy of someone who claims to help the country and yet she can’t bring herself to treat other human beings who are less powerful than she is with respect and dignity. Someone like that can really get out of control once they get in the White House. They have all that power and they become even more arrogant.”

Kessler previously penned his own book on Hillary’s time in the White House when her husband Bill was president. “She would actually, even recently, tell agents she didn’t want to see them when they were at events. She literally wanted them to hide behind curtains,” Kessler told the Herald.

Clinton has tried to portray Donald Trump as a “loose cannon” in interviews, but Byrne’s new book may actually give the presumptive GOP nominee evidence to turn the insult around on her. The Trump campaign fired off a press release yesterday saying the book provides “countless examples of Clinton not having the composure to handle the rigors of the Oval Office.” While many traditional media outlets have been reluctant to cover the book so far, Trump may force their hand if he hammers away at it during his televised rallies.

Breitbart’s exclusive report on details from Byrne’s upcoming book was published earlier this month: Secret Service Agent Book: Raging Hillary Clinton Threw Bible at Agent’s Colleague.