A former aide to a Democratic state lawmaker pleaded guilty today to helping a Virginia Republican Party official listen in on a Democratic conference call last year, and he agreed to cooperate with the federal investigation into the eavesdropping.

Joseph Willis Lee III, who had served as the campaign manager for Del. Fenton L. Bland Jr. of Petersburg, admitted that he distributed the phone number and access code of a strategy session among Democratic lawmakers, lawyers and Gov. Mark R. Warner.

U.S. Attorney Paul J. McNulty has charged Edmund A. Matricardi III, the former executive director of the Republican Party of Virginia, with eavesdropping on two such sessions. The felony charges allege that Matricardi monitored two calls and that he taped one.

Matricardi pleaded not guilty Feb. 12, saying the conference calls qualify as "open meetings" under Virginia laws. His case is scheduled to go to trial April 9. His attorney declined to comment on Lee's plea.

The case forced Matricardi out of his job and increased tensions between the two major parties last year. Claudia Tucker, chief of staff to former House speaker S. Vance Wilkins Jr., also has pleaded guilty to a misdemeanor for listening in on one of the calls.

Lee today agreed to cooperate with McNulty and federal authorities by testifying before a grand jury, providing notes and other documents and submitting to a polygraph in exchange for a reduced sentence of two years' probation and a $2,000 fine.

The two charges against Lee each carry a maximum penalty of six months in prison, a $5,000 fine and a year of supervised release. Neither Lee nor his attorney could be reached by phone tonight.

In the filing, Lee admits having received via e-mail a notification of the March 22 conference call, which had been scheduled to discuss a judge's ruling on legislative redistricting. On March 22, the plea agreement said, "Lee passed the telephone number and access code to . . . another former Democratic activist who had close ties to high-ranking officials of the RPV [Republican Party of Virginia] with instructions that she send the telephone number and access code to her high-ranking friends."

The plea document said Lee forwarded two e-mails to his unidentified friend. Both of the e-mails warned about the private nature of the meeting.

One e-mail said that "due to the sensitive nature of the meeting, and attorney-client privilege, only General Assembly members should attend or participate." The other repeated that statement and said people who join the conference call after a roll call should state their names.