Judy Woodruff:

Now to our deep dive on the continuing problem of false or misleading news, or what you might call junk news.

Much of the attention recently has centered on Facebook. And, yesterday, the company's founder and CEO, Mark Zuckerberg, told "Wired" magazine that it may take up to three years to fully prevent all kinds of harmful content from affecting people's news feeds.

Tonight, Miles O'Brien's latest report profiles a man who's been a leading purveyor of junk news, and how he has been exploiting Facebook to reach an audience.

It's part of our weekly series on the Leading Edge of technology.