Oct. 22, 209, 2009 -- Since its inception in the 1950s, the Church of Scientology has rarely been far from controversy. And now some senior insiders who have left the church are leveling disturbing accusations against the current leader, David Miscavige. Marty Rathbun, Amy Scobee, Bruce Hines and Mike Rinder each dedicated more than 20 years to the Church of Scientology, as members of the Sea Organization, or Sea Org, the equivalent of the church's clergy. They tell co-anchor Martin Bashir they left in part because the 49-year-old leader, Miscavige, struck subordinates numerous times and encouraged others to do the same.

In an interview with Bashir, scientology spokesman Tommy Davis vehemently denies that David Miscavige ever hit anyone and says the accusers are lying in an attempt to discredit Miscavige and to justify their own bad behavior within the church, which he says led to their dismissal.

Watch the full story on "Nightline" on Thursday, October 22nd and Friday, October 23rd. Co-anchor Martin Bashir reports.