The distinctive "potato-potato-potato" rumble jarred the quiet of the Veterans Day ceremony as about a dozen Harley-Davidson motorcycles rolled into the parking lot.

Those gathered to rededicate the Vietnam War Memorial in Kennewick last month turned to see what the hubbub was, and a glance at the Gypsy Joker Motorcycle Club patches on the riders' leather jackets provided the answer.

Although not all were club members, the bikers were led by Ron Campbell, 54, founder and president of the small Tri-City chapter, and they had come to join in honoring Vietnam vets.

Jokers say they are a fraternal club, simply part of a loose community of motorcycle enthusiasts.

They point out they even join in genial activities like a charitable toy run planned this weekend in Salem, Ore., to collect presents for needy children.

But police say there is a darker side to the club and its members, including those in the Tri-Cities.

They say Jokers swear allegiance to a lifestyle often at odds with society. It's why police consider the club an outlaw motorcycle gang - like the Hells Angels.

It's also why Kennewick police maintain files on the club, the Tri-City chapter and its members and associates, some of whom have criminal records.

The Gypsy Joker club was started in San Francisco on April Fool's Day 1956, but moved to Washington and Oregon after losing a sometimes bloody turf dispute with the Hells Angels in 1967.

But one retired Joker, who has been a member since 1966 but who asked not to be named, said those days are past.

"I want to emphasize that we are an organization of motorcycle enthusiasts," he said.

"Our club activities consist around brotherhood, family and motorcycle events. ... Just like any organization, you can't hold it responsible for the acts of a few."

Brian Larson of the Salem chapter became a Joker in January after hanging with the club for about four years.

He refers to the club as his adopted family and said other Joker members helped him quit drinking. "I don't even miss it," he added.

Slung over his Harley, Larson said the club is always doing something, such as making a motorcycle run to the coast, and "riding with a group of friends on the road can't be beat."

Campbell founded the Tri-City chapter in March 2001, but Jokers have been in the Mid-Columbia for decades and previously were aligned with the Spokane chapter.

Police say there are about eight members in the Tri-City chapter, but each member has "associates" who may be prospective members or simply partying friends.

The FBI estimates the ratio is typically 10 associates to each member.

In the Tri-Cities, police say associates and friends include a former Kennewick police officer, Hanford craftsmen and others. The members, including Campbell, declined requests for interviews. And some people familiar with the club also declined to be interviewed, citing fear of retaliation.

Intimidation is one reason Kennewick police Sgt. Mark Weber scoffs at the claim that club members are only motorcycle enthusiasts.

"It's a subculture in society with its own rules and chain of command," Weber said. "Their members can't differentiate between legal and illegal."

Weber has been investigating biker gangs, including the Jokers, for about 10 years in Kennewick and Kelso, where he previously worked.

"They know who I am and definitely hate my guts," he said.

He said several reported club members and associates of the Tri-City chapter have felony criminal records that include manufacturing and possession of illegal drugs, forgery and domestic violence.

Campbell recently was released after spending a year in federal prison in California for a parole violation stemming from a conviction for maintaining a building for drug trafficking. He's also scheduled to go on trial in February, facing a Benton County charge of third-degree molestation of a girl who is now 16.

Earlier this year, several people affiliated with the club were charged with first-degree kidnapping in Benton County after they allegedly beat up a 21-year-old man for talking too freely about the club and its members.

The case was eventually dismissed because the witness would not cooperate.

One Joker charged in that case was released on bail and within days was arrested for an unrelated crime after allegedly trying to pass stolen checks.

A report by a Bureau of Alcohol, Tobacco and Firearms agent said Gypsy Joker members have been involved in more criminal activities in the Northwest than any other biker gang.

In the last year, Jokers in Oregon and Washington have been arrested for firearms violations, illegal drugs, armed robberies, motorcycle theft, counterfeiting and assault, the report said.

"These are hard-core criminals," said Weber - adding homicide, arson, prostitution, identity theft, fraud and gun running to the resume of Northwest club members.

However, the Joker elder maintains, "The club is not involved with anything illegal as an organization. It's just not what the club is all about."

He's technically right, said police. Weber said the club doesn't formally sanction the crimes, and not all members or prospective members have criminal records.

The club's bylaws state: "No illegal activity by any Gypsy Joker while representing the club. Don't prostitute (the) patch."

However, Jokers are expected to back each other up.

The Joker elder recognized that not every member obeys the law, but added, "Some of the nicest guys you ever wanted to know are in this club. We're just a bunch of Harley-Davidson riders that are riding in a club."