The House Ethics Committee announced today that it has extended the contract of the outside counsel assisting with its investigation of Rep. Maxine Waters (D-Calif.) until the end of the current Congress.

It is the second time the committee has renewed its contract with Washington litigator Billy Martin, who was brought on last July to first determine whether committee members and staffers had acted inappropriately during the long-delayed Waters matter before deciding how the case should proceed.

Martin is now authorized to bill up to $500,000 for work done between now and the end of the year.

“We are fully committed to resolving this matter as early in the remainder of this Congress as is possible to do in a thorough, fair and deliberate manner,” a statement issued by acting Ethics Chairman Bob Goodlatte (R-Va.) and acting ranking member John Yarmuth (D-Ky.) said.

The extension of Martin’s contract is the latest public action taken in an ethics investigation that has been ongoing for three years.

The Waters probe began in the independent Office of Congressional Ethics, which in July 2009 voted unanimously to recommend that the Ethics Committee review Waters role in setting up a meeting between Treasury Department officials and members of the National Bankers Association, given her husband’s previous and current associations with a bank that was discussed at the meeting.

Just days before a rare public ethics trial was slated to begin in November 2010, the committee announced that “due to materials discovered that may have had an effect on the investigative subcommittee’s transmittal” it would be sending the case back to the investigative subcommittee.

The committee said in July 2011 that it had hired Martin to review Waters’ charge that the committee had violated her due process rights and to then decide whether the case against her could proceed.

“A thorough review of all of these serious allegations will be the very first task of the outside counsel’s engagement. … Outside counsel will then report his findings and conclusions to the full Committee, which will then determine whether the matter should proceed,” Ethics Chairman Jo Bonner (R-Ala.) and ranking member Linda Sánchez (D-Calif.) said in a joint statement issued at the time.

The committee announced in February that six of its members had voluntarily recused themselves from the Waters matter at Martin’s recommendation. Republican Reps. Mike Simpson (Idaho), Steven LaTourette (Ohio), Shelley Moore Capito (W.Va.), Tim Griffin (Ark.) and Goodlatte and Democratic Rep. John Sarbanes (Md.) were appointed as substitute committee members, with Goodlatte acting as chairman and existing Ethics member Yarmuth as ranking member.

It was these committee members who decided in June, based on Martin’s review, that the Waters matter had not been mishandled, clearing the way for the ethics case against the California Democrat to proceed.

“There has been no violation of due process rights to which you are entitled,” a statement from Goodlatte and Yarmuth said.

Martin billed the committee $300,000 under the terms of his initial contract, which expired Jan. 2. Last December, the House Administration Committee approved a contract that allowed Martin to bill as much as $500,000 for work through July 31, though it is not yet known what portion of the authorized amount was billed.