Kirby Brown is one of three people who died after attending James Ray's sweat lodge ceremony in Sedona in 2009.
Since then, her family has formed a non-profit called SEEK Safely – to promote a standard of ethics and safety in the self-help industry.
And Kirby Brown's sister, Jean Brown, is taking on Oprah Winfrey who helped promote Ray and his business.
Brown said her sister learned about Ray, and decided to attend one of his retreats, after watching him on The Oprah Winfrey Show.
She feels the "queen of talk" owes it to her viewers to finally address the issue.
After all, Ray served nearly two years in an Arizona prison after being convicted of three counts of negligent homicide in 2011.
"Oprah has remained silent the entire time," said Brown. "And, I just said, I feel like I need to go on the offensive here."
On May 27, Brown posted an open letter to Oprah on her blog.
She asked Oprah why she held author James Frey accountable for fabricating parts of his book A Million Little Pieces, an Oprah's Book Club selection, but hasn't touched the issue of the damage Ray has caused.
"If you address this man who lied in a memoir, that didn't really hurt anyone, how are you not addressing James Ray who ultimately killed three people?" Brown wonders.
In an interview with TV Guide, Oprah explained why she held Frey's feet to the fire: "I was defending my turf and defending every single viewer who had bought that book."
Brown says it's time Oprah questions Ray, who still appears on her website – and she on his – about Ray's deadly actions.
"Maybe Oprah has become so entrenched in this self-help realm that there's a fear of drawing attention to a big error that she made, regarding judgment and promoting someone who ultimately turned out to be a dangerous fraud," said Brown.
CBS 5 News reached out to several of Oprah's media contacts to get her take on things.
So far, we haven't heard back.
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