David Anderson, the government witness at the center of the storm involving ex-state Sen. Jerry Ward and allegations of misconduct in U.S. Sen. Ted Stevens' trial, has written a new letter to the judge in the Stevens case asserting again that prosecutors promised him and his friends immunity.

In his latest letter, Anderson offered a more detailed explanation about why he prepared an affidavit in March in which he listed 13 people whom he said were promised immunity by the government in exchange for his cooperation.

Ward, the father of Anderson's girlfriend, was on the list.

Prosecutors have denied they ever promised immunity to Anderson or anyone on his list. Anderson testified during the Stevens trial that the March affidavit was false.

The messy controversy, one of several that have erupted since Stevens' conviction Oct. 27 on seven felony disclosure violations, has become one of the grounds for Stevens' defense attorneys to demand dismissal of charges or a retrial. They called on U.S. District Judge Emmet Sullivan, who presided over the Stevens trial in Washington, D.C., to hold evidentiary hearings – essentially mini-trials – into the Anderson matter and an FBI whistle-blower complaint that surfaced Friday.

A defense attorney, Robert Cary, filed Anderson's letter in court Tuesday as an exhibit to his request for the hearing. Anderson's letter was dated Dec. 15 and follows up his first letter of a month earlier, in which he asserted his testimony refuting the March affidavit was itself false.

To read the complete column, visit The Anchorage Daily News.