Of the eight witnesses who have been granted immunity to testify in impeachment proceedings against U.S. District Judge Thomas Porteous of Metairie, one's role in the investigation has never been publicly disclosed.

Now, however, a letter from the U.S. House Judiciary Committee chairman to the Justice Department provides a link between the embattled judge and Donald Howard of Destrehan, formerly a Gulf of Mexico regional supervisor for the Interior Department's Minerals Management Service.

Turns out both were present on a November 2004 hunting trip sponsored by a Houston oilfield company that came under Howard's regulatory supervision and that was litigating a lawsuit in Porteous' court.

The trip took both men to a hunting lodge in Falfurrias, Texas, and, at least for Howard, included round-trip transportation on a Rowan Companies corporate airplane. Howard and the government agreed the gift was worth $2,495, according to court records.

Howard failed to list the trip on his annual financial disclosure forms, which certain government employees must complete to help their employers detect conflicts of interest. He pleaded guilty in U.S. District Court in New Orleans on Nov. 5, 2008, to lying to the government. Judge Jay Zainey, nominated to the bench by President George W. Bush, sentenced him to one year's probation.

Porteous did list the hunting trip on his disclosure form, valuing it at $1,000. At the time of the trip, he was presiding over a lawsuit filed against the company by one of its employees. The record in that case contains no indication that he disclosed the gift to the employee's attorney.

House Judiciary Chairman John Conyers, D-Mich., linked Porteous and Howard on the hunting trip in a July 30 letter to Attorney General Eric Holder.

The letter does not provide further details on the trip. However, one hunting lodge in the Falfurrias area, Mariposa Ranch, lists packages for hunting deer, quail, turkey, dove and nilgai, also known as blue Indian antelope.

Although the court record in Howard's prosecution does not name the company that sponsored the trip, Conyers' letter identifies it as Rowan Companies.

The letter says, in part: "Mr. Howard attended an expensive hunting trip sponsored by Rowan, which Judge Porteous also attended."

Neither Howard nor his attorney returned calls for comment Monday. Nor did a Rowan Companies representative.

The Conyers letter is included in the Judiciary Committee's application for court orders immunizing the testimony of eight likely witnesses in the Porteous impeachment proceedings. Judge Royce Lamberth of the U.S. District Court in Washington, D.C., granted the orders Aug. 12.

The others receiving immunity are: