A former FBI employee who retired due to post-traumatic stress disorder linked to time spent as a liaison between law enforcement and families of United Airlines Flight 93 victims has written a book about seeing legions of angels guarding the site after the hijacked airliner crashed on Sept. 11, 2001.

Lillie Leonardi was a Pittsburgh-area police officer before working for the FBI. She says she wrote her book, "In the Shadow of a Badge: A Spiritual Memoir" to encourage people dealing with PTSD and those who continue to look for comfort and answers about the terrorist attacks that day.

Leonardi, now a 56-year-old divorced grandmother, says she's convinced she saw the angels. But what she's questioning in her book is why she was allowed to see them.