How can you be sure that the news you see on television and read in newspapers and magazines is real and true?

We live in an age of media scandals, as we were reminded by last week’s media blitz — Katie Couric, Larry King, Bill O’Reilly, Chris Mathews — by Jayson Blair, The New York Times reporter who made up much of what he published in the “paper of record.”

We will remember again this week, while marking the anniversary of the invasion of Iraq and a war that led to persistent charges that the media doesn’t tell us the whole truth.

This is the story of another controversial invasion — and another extraordinary example of media make-believe. Let’s call it “The Brokaw Hoax.”

Early in the morning of December 20, 1989, the United States invaded Panama in search of its dictator Manuel Noriega. NBC News scrambled to cover the rapidly breaking story, with Tom Brokaw anchoring live coverage.

Brokaw conducted two chilling interviews with American businessman Roger Sizemore, said to be an eyewitness to war telephoning from the Marriott Hotel in Panama City. No camera conveyed Sizemore’s image; there was only his disembodied voice over a map of Panama, interspersed with images of the hotel and activity in the surrounding streets.

Sizemore recounted in frightening detail how Panamanian troops had entered the hotel and violently pulled people from their rooms. He reported fires burning all over the capital. He even broke news of Noriega’s capture. (The next day, The New York Times hailed Sizemore’s “chilling first-hand account.”) At Brokaw’s request, Sizemore later phoned the Today Show, and chatted at length with both Bryant Gumbel and Brokaw.

But Roger Sizemore doesn’t exist. Sizemore is actually Brian Seifert, who had been calling from the basement of his home in a suburb of Indianapolis.

How could such a hoax occur? Seifert — who has never been to Panama in his life — claims an NBC staffer woke him with a phone call, gave him a name and a script, and put him on the air.

NBC representatives say Seifert is incredible and his charges absurd. “We looked at it, analyzed it, investigated, but found no evidence that NBC was involved,” says NBC spokeswoman Barbara Levin.

“It is very possible that NBC was a victim of a hoax,” adds Executive Producer for Broadcast Services David McCormick. “But we never found evidence that a hoax was even perpetrated at all.”

Perhaps NBC should have looked harder. Seifert’s phone records show calls to NBC matching the precise times that “Sizemore” was on air. Independent analysis by a leading professional reveals that the voices of “Sizemore” and Seifert are one and the same.

Moreover, most of Sizemore’s testimony — such as his report of Noriega’s capture — was wrong. NBC’s own correspondent, Ed Rabel, who really was in the Marriott Hotel, even contradicted Sizemore’s claims moments after they were delivered.

Was NBC News a gullible victim or a willing participant? Could such a hoax happen again? Tom Brokaw declined to comment. David McCormick wouldn’t specify NBC’s screening procedures for live phone-in interviews, but did say “we were far more naïve” in 1989.

Presumably that means it’s now more difficult to telephone Tom and deliver live, on-air, and completely fraudulent reports to NBC’s audience — the only certain victims of “The Brokaw Hoax.”