Curtis was ordered to bring with him the manuscript of "Cullotta: The Life of a Chicago Criminal, Las Vegas Mobster, and Government Witness," by Dennis N. Griffin and Frank Cullotta. He was ordered to appear on May 15, but said he will refer the matter to his attorney for advice on whether to honor the subpoena or fight it.

Publishers and others often have escaped demands to testify based upon the First Amendment guarantee of a free press.

Curtis said he was initially approached about two weeks ago by an assistant U.S. attorney and asked if he would voluntarily provide the manuscript, which he declined to do on the advice of his lawyer.

He was told at that time that Rick Halprin, attorney for defendant Joey "The Clown" Lombardo, had first mentioned the book's possible role as evidence during a court hearing, but Curtis added that he had not been approached by the defense.

The 78-year-old Lombardo was one of 14 people indicted in December 2005 after a lengthy federal investigation code-named Operation Family Secrets. A jury trial is scheduled to begin next month.

The book is scheduled for publication June 1. Cullotta's co-author, Griffin, is a retired investigator and law officer who has published two nonfiction books with Huntington, "Policing Las Vegas" and "The Battle for Las Vegas." Huntington's Web site also credits him with six published mystery thrillers.

Anthony Spilotro was sent to Las Vegas in the 1970s to oversee interests the Chicago mob they had here, including the hidden ownership of certain casinos.

Cullotta, his boyhood friend, worked for Anthony Spilotro as an enforcer.

Cullotta has told journalists that he decided to become a federal witness when he learned that the crime boss had ordered him killed.

It is widely believed that the Spilotros were murdered partly because some of Anthony's subordinates were revealing secrets to law enforcement, and because both Spilotros were operating so brazenly as to attract undue attention.