It is one of the most disturbing and enduring mysteries at the heart of an organization shrouded in secrecy and plagued with allegations of abuse.
To ask about it is to risk the wrath of David Miscavige, 57, Chairman of the Board (COB) and head of the Church of Scientology.
But still the question presses. What has become of his wife, Shelly Miscavige?
Shelly was last seen in public when she attended the memorial service for her father, 'Barney' Barnett in August 2007. Those who saw her described her as gaunt, silent and shadowed by a church 'escort.'
Mike Rinder - the former Scientology spokesman now co-host of Leah Remini's Emmy Award winning show exposing the church - reported recently that an armed security detail had been hired to guard Shelly Miscavige at the church's remote compound at Lake Arrowhead, California.
Writing on his blog, Rinder stated that Robert MacLean - a man known nationally as a TSA whistleblower - had told friends that he was hired to guard Shelly. MacLean would not confirm Rinder's claim.
Now on the tenth anniversary of Shelly's 'disappearance' former Scientology 'royalty', Janis Grady, 61, who knew Shelly since childhood, has spoken exclusively to DailyMailTV.
In a unique insight into Shelly's life and character, Janis, author of the new book Commodore's Messenger which tells of her service to church founder L. Ron Hubbar, has painted Shelly as a miserable misfit, deeply affected by her dysfunctional childhood, who relished the status her role as the COB's wife and assistant afforded her.
And she has shared her own disturbing claim that 56-year-old Shelly is trapped in 'her own personal hell.'
Janis said: 'Shelly came to the ship (L Ron Hubbard's Apollo) around 1972 when she would have been around 11 or 12 years old.'
Neither of Shelly's parents joined the Sea Org but they let both of their daughters sign up at an early age. From the get go Shelly was utterly devoted to Hubbard, Janis recalled, but socially awkward and shunned by the rest of his Commodore Messengers - all teenage girls.
Shelly was not, Janis said, well educated: 'She probably went to fifth grade maybe and that was it because when she came to the ship we didn't have school. 'We had three hours of reading and writing and arithmetic but that doesn't teach you critical thinking. And she was a loner.'
Janis said: 'There was a group of younger girls and there was not a big selection of guys. The two best guys were probably Dave [Miscavige] and Marc Yager (who went onto become one of the church's most senior executives). One was short, one was tall, but there wasn't a big selection of guys and I remember a bunch of the girls competing to get Dave.
'She was moody, she was a jealous type of person.' When disgruntled, Janis said, Shelly would simply not talk to a person, sometimes giving them the silent treatment for days on end.
Miscavige was, Janis recalled, far more personable and outgoing than Shelly when the pair started dating around 1978.
Others who knew the couple have stated that they never once saw Miscavige or Shelly kiss, touch or hug each other in all their years of marriage.
Janis said: 'Like everybody they had their ups and downs, but you definitely knew that it was Dave who wore the pants in the family.
'Shelly listened to what Dave had to say.'
But, however apparently cool the relationship was, at least publicly, it was one from which Shelly benefited at first as Miscavige rose to power.
According to Janis: 'Shelly definitely had ambitions for Dave. She was very supportive of everything Dave did and I don't know if she knew this but we called her "Queen Bee," because she turned her nose up (at us all).'
