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The deaths of two missionaries at the hands of 24-year-old Colorado gunman Matthew Murray Sunday has thrust a little-known Christian group with a global reach into the public spotlight.

Youth With a Mission is a missionary group geared toward young people. It was founded in 1960 by Loren Cunningham, who created the organization after having a vision while touring the Bahamas on a gospel tour.

Today, around 20,000 members serve on short-term missionary trips in 149 countries.

Several former missionaries have accused YWAM (generally pronounced "Why-Wam") of being a cult that uses brainwashing methods.

Rick Ross, founder of the Ross Institute of New Jersey, which tracks cults, does not agree.

"Youth With a Mission is not a cult," he said. "However, I have received very serious complaints about Youth With a Mission from former staffers, family members and also others concerned, such as Christian clergy."

Rev. Jonathan Bonk, the director of the Overseas Ministries Study Center in New Haven, Conn., said that missions like those YWAM offers appeal to those looking for something other than the consumerist lifestyle.

"They want to be attached to a cosmic project that gives their little lives some kind of sense of purpose or meaning," Bonk said.

The structure of the group is decentralized, with founder Cunningham based in Hawaii at the group's University of the Nations in Kailua-Kona, Hawaii. Members must complete courses at Discipleship Training Schools (DTS) before attending the school.

The umbrella structure of the organization has given the individual training schools and their leaders great autonomy, experts said.

"Some former staffers and families of current members have likened it to brainwashing," Ross said, adding, "When I say brainwashing, I mean breaking people down and molding them into a YWAM mindset that is basically submissive and obedient and pliable to the leader's agenda."

Ross said he receives complaints on a monthly basis, many from parents who worry that their 18- to 26-year-old child — who has committed extensive time and money to an overseas mission — has fallen into a cult.

Apart from concerns about lack of health care and poor diet, the complaints include the financial straits of its members, who must pay for their missions and their DTS training by soliciting funds from friends and family.

"I've had complaints where people basically say, 'I'm getting nothing, I have nothing and if I leave YWAM, I'm basically going to leave with the shirt on my back,'" Ross said.

According to YWAM's Web site, all members — including founder Cunningham — follow this same formula of soliciting funds. But Ross said that there is no financial transparency to back that up.

"There's no independently audited financial statement," Ross said. "There's no detailed financial report that says this is how much total money — compensation — Loren Cunningham, the YWAM founder receives or his son or the DTS leader at a particular DTS in Colorado or somewhere else."

Matthew Murray, whom neighbors described as a "loner," was behind Sunday's shootings at the YWAM Denver Colorado center. Murray attended the YWAM school in Arvada briefly in 2002 according to the group, but didn't complete the 12-week DTS training because of health issues.

The Associated Press reported he had been sending the school hate mail since being kicked out of the program.

Murray also opened fire in the parking lot of the New Life Church in Colorado Springs Sunday, before being shot and killed himself by a female church security guard. YWAM maintains a center on the New Life Church grounds, the AP reported Monday.

Peter Warren, the director of YWAM, said he didn't know the shooter, nor did the victims.

"I don't think [the victims] knew him," Warren said. "But he must be going through a lot personally in his own life to do something like this."

But some are quick to caution that the act of one person does not reflect the beliefs of an entire organization. Bonk said YWAM provides adventurous young Christians with an environment to explore their calling.

"It's a way for young people to adventure within a cocoon of relative safety because there's orientation, there [are] peers, there are adults and so on and so forth," Bonk said. "So it's not as quite as risky as just setting off across the Sahara and hitchhiking or something."

The Associated Press contributed to this report.