WASHINGTON, D.C. -- When federal investigators released a report last month about the plane crash that killed Sen. Paul Wellstone, some members of Congress hoped it would dispel talk that his plane was sabotaged.

It didn't.

In Internet chat groups, political Web sites and the published reports of several leftist academics, conspiracy theories about Wellstone's death last October maintain a life of their own, particularly in northern Minnesota.

In one nasty exchange, a retired prosecutor from Duluth has threatened to take legal action against a University of Minnesota-Duluth philosophy professor who espouses the belief that the Bush White House had a hand in Wellstone's demise.

The former prosecutor, Thomas Bieter, alleges that the professor, Kennedy-assassination theorist James Fetzer, has committed "criminal defamation" by publishing articles suggesting a government coverup of the crash investigation.

Wellstone associates say they have done nothing to encourage such speculation, which some fear could trivialize the senator's political legacy and turn his memory into a morbid pop culture story.

"It's not productive," former Wellstone aide Allison Dobson said. "We're very anxious to get to the bottom of the crash, but at the same time, this sort of thing seems like chasing one's own tail. . . . We have every confidence that the NTSB and the FBI are doing their work well."

But a final report by the NTSB (National Transportation Safety Board) is months away.

Left-wing theories

When a prominent political figure dies suddenly, it isn't uncommon for rumors and speculation to spring to life. When White House lawyer Vince Foster committed suicide in 1993, for example, right-wing groups alleged that he was murdered and that then-President Clinton and First Lady Hillary Clinton covered it up.

In Wellstone's case, suspicions surfaced within days of the Oct. 25 crash near the Eveleth-Virginia Municipal Airport that killed him, his wife, Sheila, their daughter Marcia, three staffers and both pilots operating the chartered Beechcraft King Air A100 airplane.

In an Oct. 28 article published on an alternative journalism Web site under the title "Was Paul Wellstone Murdered?" Buffalo State College journalism professor Michael Niman wrote, "There is no indication today that Wellstone's death was the result of foul play. What we do know, however, is that Wellstone emerged as the most visible obstacle standing in the way of a draconian political agenda by an unelected government. And now he is conveniently gone."

In the article, posted on AlterNet.org, the professor expressed surprise that Wellstone had "lived this long."

Niman's article was also followed by a number of similar pieces in the left-wing press, notably one by syndicated cartoonist and commentator Ted Rall speculating that Wellstone was killed so Republicans could regain control of the Senate. "Did government gangsters murder the United States' most liberal legislator?" Rall wrote in a column Oct. 29.

Rall's piece has since become fodder for discussion -- and condemnation -- on a number of Web sites.

The column was followed by a piece by ex-Los Angeles police officer and journalist Michael Ruppert, who concluded in his political newsletter, From the Wilderness, that top Democratic officials are twice as likely to die in plane crashes as Republicans.

Ruppert, best known for his accusations of alleged CIA drug trafficking, called the history of plane crashes culminating in Wellstone's death "too full of coincidences."

'Conspiratorialists'

The official Washington investigation has focused on a combination of pilot error and northern Minnesota weather.

Rep. Jim Oberstar of Duluth, the top Democrat on the House Transportation and Infrastructure Committee, said the joint FBI and NTSB investigation has raised enough questions about the two pilots' approach in low cloud cover to put aside the theories of "conspiratorialists."

"Every allegation regarding sabotage was fully investigated, and the NTSB came up with no evidence of that," said Mary Kerr, Oberstar's press aide.

But the cause of the crash is still far from settled in articles and Internet discussions involving Fetzer, the Duluth philosophy professor who won a $100,000 McKnight Foundation grant in 1996 for his work in the philosophy of science.

Fetzer, an ex-Marine who has published several books and papers about the JFK assassination, opened the first of six articles in the Duluth Reader Weekly about the Wellstone crash by saying, "Conspiracies are as American as apple pie."

Discounting weather, pilot error or mechanical problems in Wellstone's flight, Fetzer's articles have seized on the possibility of sabotage brought on by a futuristic electromagnetic pulse weapon that he said could have disabled the plane's computerized components.

Evidence for this, he said in an interview, was the absence of any distress call from the pilots and the odd cell-phone experience reported by St. Louis County lobbyist John Ongaro.

Ongaro, who was near the airport when Wellstone's plane went down, has dismissed the significance of his experience, in which he said his cell phone made "strange" sounds and then disconnected.

"It's not unusual for cell phones to cut out, especially in northern Minnesota," he said.

Fetzer's articles rely less on hard evidence of any kind of murder plot than on arguing that the investigators' findings don't add up.

More provocative than Fetzer's theories about how Wellstone's plane went down are his conclusions about who was responsible.

"When I suggest Republicans may have been involved," he wrote in the Reader, "I do not mean the average GOP voter. I mean the troika that runs the government, consisting of Dick Cheney, Karl Rove and Donald Rumsfeld."

A White House spokesman said he had no comment about Fetzer's allegations. Fetzer's theories do not implicate Sen. Norm Coleman, R-Minn., who was running against Wellstone when he died. Two Coleman aides dismissed Fetzer's accusations privately but declined to make any public comment.

Fetzer's theories have caught the attention of retired St. Louis County prosecutor Thomas Bieter, who has started a critical Internet chat group called FETZERclaimsDEBUNK.

Much of the give-and-take on the Web site has been between Fetzer and Bieter, who once took a philosophy course from Fetzer and considered him a friend. The two are now bitter antagonists.

Bieter has threatened to take his case to his former colleagues at the St. Louis County attorney's office.

Chief prosecutor John DeSanto said his office would be unlikely to get involved. But that has not deterred Bieter, who said Fetzer could face civil sanctions as well.

"I simply think it's irresponsible to publish articles accusing Republicans, the FBI and the NTSB of an assassination coverup before the investigation has even been completed," Bieter said.

Fetzer said he has not spoken out about the Wellstone death as a university professor but as a private citizen.

"This is not done off the top of my head," he said. "I'm not just interested in stirring up some . . . storm. I'm interested in the truth. If I can become convinced that I am mistaken about this, I will gladly accept that and sleep easier at night. Because, believe me, the implications of this are profoundly disturbing."

Kevin Diaz is at kdiaz@mcclatchydc.com.