In late January, in the final days of the Clinton administration, the White House told the Justice Department that it was considering a presidential pardon for Rosario Gambino, a convicted heroin trafficker and reputed organized crime figure.

A law enforcement official said that a lawyer in the White House counsel's office faxed a request to the Justice Department for background information on Mr. Gambino, who is serving a 45-year sentence.

The department, which received dozens of similar requests that month, sent back a copy of Mr. Gambino's criminal record. President Bill Clinton granted no pardon.

That exchange has taken on new significance in recent days as Congressional investigators have begun to examine a $50,000 payment from a company controlled by the children of Rosario Gambino to Roger Clinton, the president's half brother.

A person close to Tommy Gambino, Rosario Gambino's son, said that Roger Clinton had led the family to believe he could help obtain a presidential pardon. ''Whatever he said to him made Tommy Gambino think it was a lock,'' this person said in an interview.

Roger Clinton's lawyer, Bart H. Williams, acknowledged yesterday that his client had received money from the Gambino family. ''Tommy Gambino is a friend of Roger Clinton's and has been for many years,'' Mr. Williams said. ''I'm not going to comment on what the payment is for or about. I am going to say it was not related to Roger Clinton's assisting Tommy Gambino's father in his parole efforts or any other effort.''

Roger Clinton did make at least one effort on Rosario Gambino's behalf, writing a letter to the parole commission in late 1998 or early 1999, Mr. Williams said.

It is not clear how seriously the White House considered granting a pardon to Rosario Gambino. A law enforcement official said the Justice Department received several dozen requests for information on possible pardon candidates in January. The White House request for information was sent by Meredith Cabe, an associate in the counsel's office.

William J. Murphy, a lawyer for Ms. Cabe, said his client processed hundreds of petitions for pardons and ''does not recall how this one came into the White House.''

Rosario Gambino of Cherry Hill, N.J., was convicted in 1984 in Newark for his role in selling two pounds of heroin to undercover agents. Prosecutors have repeatedly said that he is an associate of the Gambino crime family and a distant relative of Carlo Gambino, the late crime boss. Rosario Gambino has said he is not related to Carlo Gambino and has no ties to organized crime.

Federal and Congressional investigators have been examining Roger Clinton's role in the possible sale of pardons since January, when President Clinton granted 177 pardons and commutations on his last day in office. Soon after, Garland Lincecum, a Texan serving a prison term for fraud, surfaced saying that he had paid business partners of Roger Clinton at least $225,000 for a pardon that never materialized.

On Monday, the House Committee on Government Reform wrote to Mr. Williams asking him to explain the $50,000 payment, which was in the form of a check to Roger Clinton from a telephone company controlled by the Gambino children and signed by Tommy's sister, Anna. Mr. Williams said he was not likely to reply in detail to the letter, which he said was politically motivated and an unwarranted intrusion into his client's private affairs. The letter, he said, mentions several other people connected to Roger Clinton, none of whom received pardons.

''The letter begins by saying the committee has an interest in determining whether the clemency process under President Clinton worked and then proceeds to ask exceedingly personal questions of Roger Clinton relating to matters unrelated to pardons,'' said Mr. Williams, who declined to comment further.

Roger Clinton has denied accepting any money for pardons but has acknowledged recommending up to half a dozen ''dear friends'' for clemency. None of his requests were granted although Roger Clinton himself received a pardon for his 1985 conviction on charges of distributing cocaine.

Tommy and Anna Gambino sell private pay phones to restaurants and other establishments. They are considerably younger than Roger Clinton, who is 44. But they all live within a half-hour drive of one another in Southern California, and this week Tommy Gambino told an acquaintance he had known Roger Clinton for about four years.

According to one person close to the Gambinos, Roger Clinton called Tommy Gambino on Monday because questions were being raised about the 1999 payment.

''Don't you remember this is money you gave me for my house for a loan?'' this person quoted Roger Clinton as saying to Tommy Gambino.

Tommy Gambino, this person said, thought it best not to reply on the chance that the phone was tapped.

Rosario Gambino, 59, has made many unsuccessful legal appeals, including an effort in 1991 to have the 45-year sentence vacated and a lawsuit he brought against the parole board in 1996. He was convicted in absentia almost 20 years ago for drug trafficking by Italian authorities who are seeking to extradite him, now that he is eligible for parole.

His children say his sentence is much longer than it would have been under guidelines that have been in place since 1987, because the amount of heroin in question was relatively small.

''He would have a powerful argument that under the present-day guidelines, he'd be on release now,'' said Herald Price Fahringer, a lawyer who represented Rosario Gambino in a 1986 appeal.

Family members are said to be debating how much to say about Roger Clinton.

''We're trying to decide whether to take a shot with this,'' said a person close to the family. As much as they think it might help their father, ''it kind of goes against the Gambino grain to rat anyone out.''