Bernard Kerik, the former police commissioner, resigned yesterday from Giuliani Partners, the corporate security and investment consulting firm run by Mayor Giuliani, where he had been an executive since 2002. Mr. Kerik, in a brief statement to the press, said he was doing so “to take time off to focus on my family and to clear my good name.”

Mr. Kerik said he had resigned directly to Mr. Giuliani “effective immediately,” and that he had also apologized to him for the manner in which he had withdrawn from consideration to be secretary of homeland security in the Bush administration. Mr. Kerik said he would pursue unspecified business opportunities in the future.

Mr. Kerik withdrew as a candidate for the homeland security post on December 11. Since then, Mr. Kerik has been the focus of an almost daily series of public revelations about his private life and business dealings. Specifically, questions have developed about Mr. Kerik’s sale of nearly $6.8 million worth of stock options in Taser International, a company that does business with the Homeland Security Department.

At a press conference, Mr. Giuliani said, “He made the right decision. I think he had evaluated it correctly.”

Giuliani Partners has removed Mr. Kerik’s name from its Web site, and released a statement saying that Giuliani-Kerik LLC, the joint venture of which Mr. Kerik had been CEO, was being renamed Giuliani Security and Safety.

An executive at the firm who had been fire commissioner under Mr. Giuliani, Thomas Von Essen, was asked by a reporter on NY1 News if Mr. Kerik had “brought this on himself.” He said, “absolutely.”