LOS ANGELES ? The mother of the Colorado boy once feared missing aboard a runaway helium balloon has admitted to investigators that the saga that gripped much of the United States was a hoax, court records showed.

Larimer County Sheriff Jim Alderden already said last week that eccentric amateur scientist Richard Heene and his Japanese-born wife Mayumi fabricated the October 15 "balloon boy" drama when their six-year-old son Falcon was reported to have flown away in the flying saucer-like homemade aircraft.

He said the couple was expected to face felony and misdemeanor charges. Their three sons ? aged 10, eight and six ? were unlikely to face charges because of their age.

Mayumi Heene told investigators two days after the incident that she and her husband "had lied to authorities," according to a copy of a search warrant affidavit published Saturday in The Coloradoan, a Fort Collins newspaper.

"The motive for the fabricated story was to make the Heene family more marketable for future media interest," the affidavit stated.

It was Mayumi who called police to report that Falcon was inside the silver balloon launched ? allegedly by accident ? from the backyard of the family's home, it said. Before calling 911, her husband had already placed frantic calls to a local TV station and federal aviation officials.

The Heenes, who starred in the reality television series "Wife Swap" earlier this year, devised the balloon hoax approximately two weeks before it took place and instructed their three sons to "lie to authorities as well as the media regarding this hoax," the affidavit added.

Richard Heene's publicity stunt, which police say was aimed at landing him a reality television show, had mesmerized US networks as they scrambled to broadcast live footage of the windswept balloon and rescue attempts watched by millions.

But the public's sympathy turned to skepticism and then outrage when the boy emerged from the attic of his home's garage and later told CNN that the family had done it "for the show."

During an October 17 search of the Heene home, authorities seized video cameras, cassette tapes, computers, hard drives, a photograph of a flying saucer, receipts, papers and a flight itinerary, a return of search warrant showed.

On "Wife Swap," the Heenes and their children were portrayed as a family of storm-chasing amateur scientists who conduct wacky experiments, from launching rockets to searching for extra-terrestrials.