With David Letterman and Conan O’Brien in repeats, ABC’s “Nightline” returned to first place in Total Viewers ahead of CBS’ “Late Show” and NBC’s “Tonight” show, a position it last held in early September. Letterman remained in first place in the A25-54 demo. All three programs were down in viewers from the previous week.

Last week, “Nightline” ran a series of episodes about Scientology, which culminated in a spokesperson walking off during an interview with Martin Bashir. That episode drew 4.25 million viewers Friday night.

The numbers for the week of October 19: