Though he hoped to spark an armed revolution, Timothy J. McVeigh ended up weakening the anti-government militia movement, whose visible membership has declined since the Oklahoma City bomber's capture and trial, experts who monitor extremism said yesterday. Militia members expressed a cool indifference about McVeigh's fate, saying he stigmatized their cause and is no martyr.

"As far as McVeigh's concerned, we couldn't care less. We don't give a damn," said Ed Brown, a spokesman for the Constitution Defense Militia, based in Plainfield, N.H. But Brown, like many other conspiracy theorists who inhabit the right-wing fringe, contended that McVeigh's trial for blowing up the Alfred P. Murrah Federal Building and killing 168 people was a sham and that McVeigh was "assisted in the bombing by criminals within the United States government."

McVeigh's deadly act of terror brought unwelcome attention to paramilitary units that once existed in nearly every state and were ready to wage war with federal agents -- whom they saw as poised to grab their guns and crush their civil rights. Militia ranks grew dramatically after the bloody FBI sieges at Ruby Ridge, Idaho, and near Waco, Tex. -- events that McVeigh's lawyers said motivated his rage -- but the groups now appear to be far less active, and their existence doesn't generally worry the FBI.

"Most of the militia organizations around the country are not, in our view, threatening or dangerous," FBI Director Louis J. Freeh testified before the Senate Judiciary Committee two days after a Denver jury convicted McVeigh of the bombing. The majority of militia members are nonviolent and some have assisted the bureau in its investigations, he said.

The Anti-Defamation League and the Southern Poverty Law Center, which monitor hate groups, report that many militia members have dropped their affiliations, joining "Common Law" groups instead and clogging the courts with nuisance suits. About 15,000 people belong to militias nationwide, by the ADL's estimate, although such numbers are difficult to verify.

McVeigh traveled the gun-show circuit but reportedly was kicked out of the only militia meeting he attended in Michigan. "The bombing already had its effect on the movement -- they have disassociated themselves from McVeigh. The trend is toward a diminishing of militia activity," said Richard Baudouin, a spokesman for the Klanwatch project of the Southern Poverty Law Center in Montgomery, Ala. "We don't think the verdicts will have any effect on the above-ground movement."

More worrisome to federal authorities are a small number of underground, "leaderless cells" of the extreme right that advocate bank robbery, bombings and the violent overthrow of the government. Like McVeigh, they draw inspiration from "The Turner Diaries," a racist, antisemitic novel about revolutionaries who blow up the FBI building. In an earlier hearing, Freeh expressed concern that "law-abiding" militias might be infiltrated by more hardcore extremists to "further their own terrorist agendas."

Among many in the "patriot" movement, McVeigh's guilt is not disputed, but the case is hardly closed. "Most of my listeners seem to agree that McVeigh deserved the death penalty for his role, but that others were involved and they should be nabbed," said Tom Valentine, host of a shortwave talk show called Radio Free America, based in Fort Myers, Fla.

The ever-suspicious Internet remains rife with theories that several "John Does" were involved in the bombing. Many view McVeigh as a "fall guy" and "patsy," said Dave Trochmann, co-founder of the Militia of Montana. "There are so many unanswered questions that to put this thing to rest just because McVeigh's been found guilty would be a bad disservice to the citizens of this country."

Tony Sgarlatti of Hopkins, Minn., is selling an "Oklahoma City Bombing Fact Pak" ($29.95) via a site on the World Wide Web. It offers alternative theories on the April 19, 1995, blast, including allegations that the explosion came from bombs planted inside the Murrah building. His latest theory is that an "electromagnetic pulse weapon" was involved. Other Web sites carry photos of a Ryder truck parked at a military installation in Oklahoma, where conspiracy-minded investigators contend the fertilizer bomb was assembled.

The Oklahoma National Guard confirmed Friday that the aerial photos were indeed taken above Camp Gruber in the fall of 1994 and said the classified project involved weapons sensors and was overseen by the Defense Advanced Research Projects Agency. The National Guard's statement said the truck "had no association whatsoever with the tragedy at the Alfred P. Murrah Building."

Sgarlatti, a member of the non-armed Citizens for a Constitutional Minnesota, does not buy the official line. "I don't believe McVeigh was the mastermind in doing all of the tragic stuff that occurred. If he's killed, of course, the answers are going to go to the grave with him."