The father of Scientology leader David Miscavige told us why he left the church he calls a 'cult' (and showed us his family photo album)

Ever since the death of L. Ron Hubbard in 1986, the Church of Scientology has been led by David Miscavige, one of Hubbard's former messengers.

Miscavige's reign atop Scientology has been turbulent. The church successfully gained tax-exempt status in the US when the IRS accepted it was a religion - saving it millions of dollars. And Miscavige brought Tom Cruise, the world's most famous actor, into his fold.

But Scientology has also been beset by scandal: Miscavige's wife, Shelly, disappeared from public view in 2006 and has not been seen in public since. Some of Scientology's most famous adherents, like actress Leah Rimini, and writer/director Paul Haggis, have publicly split with the church. Dozens of former Scientologists have fled the church's vast "Gold Base" HQ in Gilman Hot Springs, California, claiming they were coerced and abused for years inside its fences. And a book and an HBO documentary, both titled "Going Clear," painted a brutal picture of intimidation, beatings, imprisonment, and exploitation of Scientology workers. (The church regards these stories as false claims made by disgruntled former members who have personal axes to grind, or unaddressed mental issues.)

Now Miscavige's father, Ron, has written a book about his life inside the church, titled "Ruthless." Ron describes David as a dictator, the leader of a "cult" who suppresses any dissent, keeps his flock in poverty, and suggests that he may be a sociopath.

In 2012, Ron and his wife secretly loaded up their car, dodged Scientology's security guards, and fled Gold Base, never to return. He has not seen his son - or any of the other members of his family still inside the church - since. In 2013, Ron discovered he had been followed for over a year by two heavily armed private investigators. They told police they were paid by Scientology to keep tabs on Ron. The church denies their claims.

Ron Miscavige spoke to Business Insider recently about what it's like to be the exiled father of the world leader of Scientology, what life is like inside the church, and where he thinks Shelly Miscavige is now. He also gave us a selection of old family photos: They show David as a normal American kid growing up in New Jersey, years before he became the unquestioned dictator of a religion based on the belief that we are all Thetans, brought to the planet Teegeeack by the galactic dictator Xenu, before our home was renamed "Earth."