TWO YEARS INTO the controversy over the Air Force's botched and misguided deal to lease refueling tankers from Boeing Co., the full story still isn't known. Defense Department Inspector General Joseph E. Schmitz's report on the tanker deal, released this month, is as notable for its lapses and omissions as for its discoveries.

The report is valuable in finally putting to rest the lone-actor theory of the $30 billion deal: the notion, peddled by the Air Force, that any problems with the proposed tanker lease were the sole fault of former procurement official Darleen A. Druyun, who was negotiating with Boeing over tankers while angling for a job at the company. The odiferous nature of the arrangement, in which the Air Force maneuvered to obtain overpriced planes in a way designed to disguise their real cost, was succinctly put in an e-mail from one official: It was not only a "bailout for Boeing" but one that would "screw the taxpayer." Mr. Schmitz's report skewers a number of senior officials -- including former Air Force secretary James G. Roche and former defense undersecretary Edward C. "Pete" Aldridge Jr. -- for evading established procurement procedures.

But investigators failed to interview Mr. Aldridge, despite the central role he played. Mr. Schmitz told the Senate Armed Services Committee at a hearing this month that his investigators tried: They sent Mr. Aldridge registered letters and left telephone messages at his home. This is a man who sits on the board of a major defense contractor. How hard could it have been to find him -- and why not use the inspector general's subpoena power if needed?

Likewise, while investigators spoke with Defense Secretary Donald H. Rumsfeld and former deputy defense secretary Paul D. Wolfowitz, none of their comments were included in the report, Mr. Schmitz testified, because they hadn't said anything "relevant." If so, investigators must not have asked the right questions. To offer just one example: Mr. Roche recounted that Mr. Rumsfeld called him in July 2003 to discuss his then-pending nomination to be secretary of the Army and "specifically stated that he did not want me to budge on the tanker lease proposal."

Moreover, Mr. Schmitz didn't question anyone outside the Defense Department about the tanker deal, though the White House -- including President Bush and Chief of Staff Andrew H. Card Jr. -- was involved. White House officials "see increased pressure and realize a political downside to not moving forward with tankers," one Boeing official wrote in an e-mail, noting that House Speaker J. Dennis Hastert (R-Ill.) had called Mr. Bush to press for the deal. Mr. Schmitz says his mandate was just to assess responsibility within the Defense Department; even so, wouldn't the conduct of other officials be relevant? And if the White House is off-limits for interviewing, why did Mr. Schmitz submit his report to the White House for review before its release?

The report is riddled with unsupportable redactions, vast swatches of blacked-out sections that deal, among other things, with White House involvement in the tanker lease. Some of this information was given to Senate investigators under an agreement that it remain confidential, but Mr. Schmitz was not bound by that compact. He simply took it on himself to keep that and other relevant information from the public.

Sen. John McCain (R-Ariz.) and the other members of the Armed Services Committee who refused to be worn down by years of Defense Department stonewalling should now persist in getting the full report on the record and completing the job that Mr. Schmitz started. At the start of the June 7 hearing, committee chairman John W. Warner (R-Va.) called the tanker lease affair "the most significant defense procurement mismanagement in contemporary history." Surely then it's his committee's responsibility to trace responsibility up the chain of command.