Attorney General Cuomo is ramping up his pay-to-play investigation into the comptroller office’s management of the $154 billion state pension fund, announcing yesterday that he intends to use the same powerful legal weapon that his predecessor, Governor Spitzer, famously wielded against Wall Street companies.

Unlike Mr. Spitzer, who dusted off the 86-year-old securities statute to uncover and prosecute financial fraud committed by businesses, Mr. Cuomo is bringing the law to bear on a new arena, a public corruption case.

Aides to Mr. Cuomo said the attorney general’s decision to use the statute to bolster his probe of conflicts of interest involving the pension fund under the tenure of a disgraced former comptroller, Alan Hevesi, marks the first time that a New York attorney general has turned the law against government officials.

“The Attorney General has invoked jurisdiction under the Martin Act to investigate certain matters relating to the New York State Common Retirement Fund, which is operated by the New York State Comptroller,” a spokesman for Mr. Cuomo, Jeffrey Lerner, said in a statement.

“The Martin Act empowers the Attorney General to investigate fraud in the purchase or sale of securities and to bring civil and criminal charges where appropriate,” Mr. Lerner said.

Mr. Cuomo’s office is specifically focusing on millions of dollars in referral fees that investment firms connected to the pension fund funneled to a financial services firm linked to Hevesi’s close political adviser, Hank Morris.

The district attorney of Albany County, David Soares, is conducting a separate probe of the comptroller’s office.

In January, Hevesi resigned in disgrace after pleading guilty to defrauding the state by using a state employee to run errands and chauffeur his wife.

Mr. Cuomo’s use of the statute is the strongest indicator that the attorney general is significantly widening his probe.

The law will enable him to increase his leverage over companies that invest pension fund dollars, helping him map out how money flowed from investment firms to other companies affiliated with people close to the former comptroller. The power of the statute could also pave the way toward examining pay-to-play allegations involving pension funds in other states.

In July, the New York Times reported that investigators are looking into whether Hevesi’s children illegally profited from Hevesi’s control of the pension fund. The article noted that a hedge fund, Third Point Capital, hired Hevesi’s elder son, Daniel, months after the comptroller’s office agreed to invest pension money in a fund that invests in Third Point.

The Times also reported that investigators are reviewing details of political contributions made by investment firms and executives to Hevesi’s son, Andrew Hevesi, an assemblyman of Queens.

The Martin Act of 1921, named after its obscure legislative sponsor, Louis Martin, can be invoked in connection with the fraudulent sale of securities.

The statute was thought to be one of the weakest versions of the Blue Sky laws that states passed to combat fraudulent securities schemes but expanded in power over the years, largely thanks to court decisions upholding it.

Mr. Spitzer stood apart from his predecessors by using the statute’s broad powers to investigate financial giants. He employed it most famously to unearth internal Merrill Lynch e-mails that led to charges that company analysts provided biased investment advice.

“The law gave the attorney general a whole range of civil powers,” Brooke Masters wrote in her biography of Mr. Spitzer, “Spoiling for a Fight.” He “could subpoena documents, haul brokers and investment bankers in for public questioning, and unlike his federal counterparts at the SEC and the Justice Department, he didn’t have to specify up front whether he was going to seek criminal charges or file an easier-to-prove civil case.”

That targets receiving a Martin Act subpoena are in the dark about the type of charges they face puts enormous pressure on them to cooperate and avoid a potentially devastating criminal indictment.

The statute also doesn’t require proof of fraudulent intent — a difficult legal hurdle to pass — or, as Ms. Masters noted, that money exchanged hands.

In another sign of his office’s expansion of the probe, Mr. Cuomo’s investigators last week brought in for questioning Dennis Tompkins, the top press aide to Comptroller Thomas DiNapoli, a former assemblyman was appointed by the Legislature in February to replace Hevesi.

A source said the questioning of Mr. Tompkins largely related to the disappearance of paper documents from the desk of David Loglisci, a former deputy comptroller who was hired by Hevesi to oversee pension fund investments.

Mr. DiNapoli, through his press office, issued a statement on July 16, saying that shortly after Mr. Loglisci resigned from his post, “my staff discovered certain records were missing from Loglisci’s desk.” He said most of the documents were later recovered and turned over to investigators.

The source said investigators were interested in the circumstances behind the comptroller’s office public assertion that there only one set of documents.