​Rudy Giuliani, the cloud hanging over the storm in New York gubernatorial politics this week, has actually been playing a big role in an ongoing race for governor next door, appearing endlessly for New Jersey GOP candidate and mirror image Chris Christie. A Times story this morning about a mob tie hidden in the family albums of former U.S. Attorney Christie makes him and Giuliani genealogical bookends as well.

The Times' David Halbfinger and David Kocieniewski uncovered the fact that the brother of Christie's aunt's husband, Tino Fiumara, is a ranking member of the Genovese crime family twice convicted of racketeering and sentenced to 25 years in the pen. When my biography of Giuliani was published in 2000 (Rudy! An Investigative Biography, Basic Books), I revealed that Giuliani's father, uncle and cousin were awash in mob ties, and that his cousin had actually been shot and killed by the FBI right around the time that Rudy was making his way through deep FBI background checks for Justice Department jobs.

What's so intriguing about the secret in Christie's closet is the explanation he gave the Times for why it stayed there in 2002, when he was cleared by the FBI to assume the top prosecutorial post in New Jersey...

Fiumara was under investigation at that very moment by the office Christie would soon take charge of, suspected of aiding the flight of a fugitive under investigation for murder. When Christie took office, he recused himself but "never revealed his connection to the defendant or his sensitive decision to distance himself from the handling of the case."

That's odd enough. But what's really odd -- and potentially a violation of law -- is that Christie told the Times that "his relationship to Fiumara never came up in his FBI background check " and that "he never raised it, though he assumed investigators were aware of it."

I looked deeply into the question of FBI background checks when I did the Giuliani biography. A former FBI agent familiar with background check procedures told me the obvious: if the FBI independently found out about the criminal histories of Rudy's relatives "they would have surely informed him" during the clearance process. Christie and Giuliani had every reason to know that their secrets were safe when the FBI didn't mention the ties.

Former Justice Department Inspector General Michael Brombwich said that he had to undergo a background check similar to Rudy's and remembers being asked by FBI agents to volunteer any potentially scandalous information about his own or his family's history. "I pretty clearly recall that I was asked that -- is there anything about your background or anything about your associations that might prove embarrassing if it were publicly disclosed?"

Brombwich said that the onus was on the candidate for the Justice post. "It's up to the discretion of the person, the judgment of the person," he said "That way, if you're the person doing the background, you can't be accused of engaging in a witch hunt. You're basically asking them to provide you with the information that they think is relevant and that they think may be germane."

I remember my many talks with Harold "Ace" Tyler when I wrote the Giuliani biography. Tyler, a former federal judge who was Deputy Attorney General in the Ford administration, was a pivotal figure in Rudy's life. He brought him to Washington in the mid 70s to be one of his top assistants in the Justice Department, and when Ford was defeated, he gave Giuliani his first job in private practice, at a New York law firm where Tyler reigned. Tyler was baffled when I told him what I had unearthed about Giuliani's family.

"I never heard of any such fact -- if it were a fact -- that he had a cousin or any other relative that was charged with having a criminal history of some sort," said Tyler, who has since died. "I would be surprised to hear that there was something developed at that time, because I think I would have heard about it from the FBI, but I did not. I never heard of anything like that."

Giuliani has been so close to Christie during the campaign that he endorsed him back in February, at a press conference near Governor Jon Corzine's home, did robocalls for him, and even appeared on Fox and CNBC with him. It is a violation of federal law to mislead FBI agents during any kind of an investigation, including background checks.