Could Harper Lee have written four books?

With Tuesday's release of "Go Set a Watchman," Harper Lee now claims two published books under her belt. Now the literary world is buzzing about the possibility of two more novels.

Story highlights

  • Harper Lee is the author of "To Kill a Mockingbird" and "Go Set a Watchman"
  • Her lawyer hinted this week at a third, as-yet-unpublished novel
  • An historian and friend of the author spoke to CNN about the possibility of yet another book

Monroeville, Alabama (CNN)Until recently, Harper Lee was a one-book author, albeit the writer of one of America's most popular novels, "To Kill a Mockingbird."

With Tuesday's release of "Go Set a Watchman," she now claims two published books under her belt. But are there more?
In an op-ed this week in The Wall Street Journal, Lee's attorney, Tonja Carter, hinted at a third, as-yet-unpublished novel. And a friend of the author, who is also a professor of history at Auburn University in Alabama, spoke to CNN about a possible fourth book.
    Wayne Flynt said he'd spoken with Lee's sister before her death about the mystery manuscript.
    "Her sister, Louise Conner, told me and my wife that she (Lee) finished the novel sitting at her dining room table in Eufaula, Alabama. Louise said she read it and it was far better than 'To Kill a Mockingbird' or 'In Cold Blood,' " he said. "Somewhere out there at least one person, her sister, says there was a book far superior to either one of those classic books."
    The possible nonfiction novel even had a name, "The Reverend."
    It supposedly chronicles the true-life story of Rev. Willie Maxwell, who was suspected in the deaths of various relatives, Flynt said.
    Years ago, Lee went so far as to interview a doctor about poisons to find out which could cause someone to die but not be found in an autopsy. Flynt says he knows about the conversation because he spoke to the doctor.
    But one person he's never spoken to about the possibility of a fourth book is the author herself. Flynt says he's never wanted to intrude on Lee's privacy.
    In March, the New Yorker similarly reported on the possibility of a book about the Rev. Maxwell. The family of Maxwell's lawyer shared with the magazine what they say is a chapter of the book Lee sent to the lawyer. That lawyer died in 2011.
    Asked whether he thinks "The Reverend," will ever see the light of day, Flynt said he's not sure.
    No one seems to know where the book is or if the book in fact exists.
    "Could she have given a copy of the manuscript to somebody, and somebody's been sitting on it all these years, and will the publication of 'Go Set a Watchman' drag it out of wherever it is? I don't know. Will it be found as Tonja Carter, the lawyer, goes through more and more of Alice's papers?" Flynt asked, referring to another one of Lee's sisters.
    "Could we go from a one-book author that everyone assumed would never write anything else, to a four-book author?"