Fox "America's Most Wanted," with host John Walsh, recently marked 20 years on the air. "On AMW,' I see some incredible, immediate results," Walsh says.

NEW YORK — When he started "America's Most Wanted," John Walsh could point to at least one thing in its favor: Society's swampland of bad people doing bad things would never run dry. On that basis, the show seems a cinch to run forever.

It recently marked 20 years on the air. And this week it observes another milestone: arrest of the 1,000th fugitive targeted by "AMW" since April 1988 — Dwight Smith, a New York real estate agent accused of murdering a friend over a deal gone awry.

Smith was on the lam for nearly a year. Then, on April 19, an anonymous caller who had recognized him on the "AMW" Web site disclosed his whereabouts: an address in Richmond, Va. That night, Smith was in police custody.

Airing from Times Square, this special edition of "AMW" may have a more festive feel than usual (especially since the show has logged 21 more captures in the meantime). But Walsh is under no delusions the larger fight is over, or will ever be won.

"I know firsthand that lots of people get away with murder," he states flatly.

He found that out when his 6-year-old son Adam was abducted and murdered in 1981. The investigation was botched. No one was charged with the crime. The likely killer died in prison, where he was serving time for an unrelated crime. Adam got no justice.

"But on AMW' I see some incredible, immediate results," Walsh says, "where you really do catch somebody. Get some justice. And maybe save lives: You know, some killers are gonna continue until they get caught."

A former Florida hotel developer, Walsh, 62, has spent a quarter-century as a crusader for tougher laws against sex offenders, more cooperation among law enforcement agencies, and citizen involvement in flushing out fugitives.

"Now, join the manhunt!" exhorts a husky-voiced announcer at the top of "America's Most Wanted," which keeps its 6.2 million viewers abreast of heinous new crimes, the names and faces of suspects, and the arrests that result from this "AMW" dragnet.

"I see the worst of society during the week," Walsh is fond of saying, "and then, on a Saturday night, I see the best of society: people doing the right thing, making the call."

"All the people who are with me on this show and this mission, we have changed the process of how law enforcement deals with missing children, missing adults, rape cases and serial killers," he declares.

"It's not about closure, there's really no such thing as closure," Walsh explains. "It's seeing the person who destroyed your life, or a loved one's life, being held accountable. And I still love it. I'm more driven than ever."