Governor Spitzer may always be known as the “Sheriff of Wall Street,” but as he faces a probe into his alleged links to an elite prostitution ring, the nickname could transform into a sarcastic epithet to be tossed around gleefully by the many enemies he collected during his years as state attorney general.

In that role — the one that won him fame as a crusader against excesses on Wall Street and eventually helped vault him to the governor’s mansion — he seemed to relish digging up dirt on some of the richest and most powerful men in the country. The legal battles he waged against such giants as Richard Grasso, a former chairman of the New York Stock Exchange, and Maurice Greenberg, a former chief executive of American International Group, often turned nasty and personal.

Mr. Spitzer was once accused of telling a former chairman of Goldman Sachs, John Whitehead, “I will be coming after you,” after the executive published a letter that was critical of Mr. Spitzer’s tactics with Mr. Greenberg, who had been accused of misleading investors. Mr. Spitzer denied making threats, although through a spokesman he did admit to calling Mr. Whitehead after the critique was published.

When he went after Mr. Grasso over the size of his compensation package while he was the NYSE head, Mr. Spitzer allegedly had prosecutors grill Mr. Grasso about whether he had had an extramarital affair, a new book says.

In the book, “King of the Club,” by Charles Gasparino, the author writes about an interview in which investigators asked Mr. Grasso if he had fathered an illegitimate child by “his best friend growing up.” Mr. Grasso is reported to have been incensed at the question, and to have said, “No.”

The case against Mr. Grasso was deemed unusual at the time, as government prosecutors previously had rarely monitored the size of executive salaries.

Now, Mr. Spitzer’s career is at risk of following the arc of the many rich and powerful men he took down.

“He actually believes he’s above the law,” a former NYSE director, Ken Langone, was quoted as saying in the Wall Street Journal yesterday.

While the news prompted a round of applause on the floor of the New York Stock Exchange yesterday afternoon, according to a report by CNBC, most of Mr. Spitzer’s former targets seemed unwilling to comment on the allegations now facing their nemesis.

Mr. Greenberg declined a request for an interview, and Mr. Grasso did not return messages.