PHOENIX — The U.S. Border Guard was among the last known groups of armed civilians actively patrolling the Arizona desert on the lookout for illegal immigrants and drug smugglers.

Now that its leader, former neo-Nazi Jason Todd "JT" Ready, is dead in what police believe is a murder-suicide involving his girlfriend in a quiet Phoenix suburb, the future of his group has suddenly come into question.

His friends vowed Friday that the patrols will continue in some form.

Sean Rose, who said Ready was like a brother, said he would quit his job to keep the group going. "He did a lot for this country as far as protecting the border, something the government doesn't do," he said.

Groups that monitor activities of organizations like the U.S. Border Guard expressed doubts that it will be able to maintain its operations. Without Ready's leadership, they say, the Border Guard will likely disappear.

"The U.S. Border Guard is probably finished," said Mark Potok of the anti-hate group, the Southern Poverty Law Center. "It really did revolve around JT Ready."

An SPLC recent report said that "nativist extremist" groups like Ready's decreased by almost half in 2011 to 184 groups, down from a high of 319 such groups in 2010.

The Minuteman Project and other similar groups have been plagued by infighting and financial difficulties, largely splintering or disintegrating altogether.

The movement's decline comes as states like Arizona passed harsh immigration laws that included provisions allowing local police to question a person's immigration status while enforcing other laws, Potok said.

Those laws created an impression among some civilian border militia members that state governments were doing more about illegal immigration, and that they no longer had to, he said.

Jennifer Allen, interim director the Arizona chapter of the immigrant advocacy group, the Southern Border Communities Coalition, said that organizations like Ready's thrive on a charismatic leader, and tend to implode once that leader is gone.

"What brings hate groups together is anger and fear. So it makes sense that they would start to direct that toward one another," she said. "They also attract a lot of people that want to be mega personalities.

"And it ends up being their own worst enemy — fighting over the limelight," she said.

The SPLC also cites the case of Shawna Forde, a former member of the Minuteman Civil Defense Corps. She was convicted in a home invasion that left a 9-year-old girl and her father dead.

Prosecutors said the invasion was an attempt to steal drug money to fund her group's border operations.

Forde was expelled from the Minuteman group in 2007 amid allegations of lying and pretending to be a senior leader. At the time of the killings, she was the head of her own group called the Minutemen American Defense.

The SPLC's report said the killings cast a pall over the entire civilian border militia movement.

Ready and members of his group would dress up in head-to-toe camouflage gear, helmets and boots, and carry high-powered guns as they traveled out into the desert to look for illegal immigrants or smugglers.

Rose said that he never joined the group on patrols, but that he and Ready would go out with a handful of others about a dozen times a year on similar outings.

Rose and other friends of Ready's said they are reluctant to believe that he killed four people and himself, and say they feel drug cartels are more likely to blame even though police have discounted that possibility.

Police say all the evidence points to a domestic-violence situation.

Those killed in the rampage in Gilbert on Wednesday were Ready's girlfriend, her daughter; her 16-month-old granddaughter; and her daughter's boyfriend.

Harry Hughes, another close friend of Ready's and a regional director with the Detroit-based National Socialist Movement, said he plans to continue his own one-to-two man desert patrols.

Members of the NSM promote white separatism, dress like Nazis and display swastikas. They believe only non-Jewish, white heterosexuals should be citizens and that anyone who isn't white should leave "peacefully or by force."

Ready was a former member of the group.

"Just because Mr. Ready is no longer with us doesn't mean we're going to stop," Hughes said. "After we pay our last respects and get our ducks back in a row, I'm pretty sure business will continue."

He added, "I don't think JT would have wanted us to stop."