An investigation into possible criminal charges for a couple who told authorities their son floated off in a balloon shaped like a flying saucer has spread to those who worked with them.

Robert Thomas told sheriff's investigators about what he observed between amateur storm chasers Richard and Mayumi Heene when he helped record the husband's ideas earlier this year, said Thomas' attorney, Linda Lee. Thomas earlier sold his story to the Web site Gawker.com.

Lee said Richard Heene was "obsessed" with trying to land a TV show and become famous.

"Heene believes the world is going to end in 2012," she said. "Because of that, he wanted to make money quickly, become rich enough to build a bunker or something underground, where he can be safe from the sun exploding."

SLIDESHOW: View photos from the alleged hoax

Thomas told NBC television Tuesday that he had nothing to do with the hoax and didn't know about the balloon being launched until he saw it on television. Asked whether he should be profiting by selling his story, Thomas, who described himself as an entrepreneur and a college student, said he was told that people sell their stories to the media and that he was paid "way less than most people think."

Larimer County investigators have been poring over e-mails, phone records and financial documents from the Heene home as they ponder charges against the Heenes.

The Federal Aviation Administration has opened its own investigation into the balloon flight, spokesman Mike Fergus said Tuesday. He said the inquiry began either Friday or Monday, but he didn't know how long it would take.

Fergus said the FAA investigates only civil allegations, rather than criminal ones. He declined to provide details.

The balloon landed near Denver International Airport, and some flights had to be changed to a different runway for 20 minutes.

The sheriff's office said its findings will be forwarded to prosecutors next week to decide if the Heenes should be charged with falsely reporting that their 6-year-old son, Falcon, had drifted away in a large home-built helium balloon to drum up publicity for a reality TV show.

The investigation could reach beyond the Heenes.

Sheriff Jim Alderden said documents show that a media outlet had agreed to pay the Heenes. However, it was unclear if the outlet was a conspirator. Alderden didn't name the organization.

Richard Heene emerged briefly from the family's home Tuesday morning but didn't answer reporters' questions.

He showed two delivery workers where to find five helium tanks that were being returned to Flexx Productions, a Fort Collins rental company, because the lease was up.

The workers said four of the tanks were empty and one was partially full.

The Heenes apparently wanted to star in a reality show focusing on a range of bizarre experiments, such as trying to attract UFOs with a weather balloon. Thomas worked with Richard Heene on the idea for the show from March until May.

Sheriff's officials interviewed Thomas on Sunday, after he revealed that Heene had been planning a media stunt to promote the show, Lee said.

Thomas' notes include Richard Heene discussing a hoax that involved a balloon, Lee said.

Lee said investigators told her Thomas would not face charges, but she was seeking immunity for him "just to be safe." Thomas has said he had no idea that a possible hoax would involve the Heene children.

Richard Heene's attorney, David Lane, declined to say directly whether he believes the incident was a hoax but said the Heenes are innocent until proven guilty. The Heenes didn't comment Monday.

Mayumi Heene's lawyer, Lee Christian, declined to comment on whether the couple still maintains they thought their son was in the balloon before he emerged at home and told reporters he'd been hiding in the garage.

Alderden said the children were still with the parents and that child protective services had been contacted to investigate their well-being.

Alderden said charges he is seeking against the Heenes include conspiracy, contributing to the delinquency of a minor, making a false report to authorities, and attempting to influence a public servant. The most serious charges are felonies and carry a maximum sentence of six years in prison. Alderden said authorities also would be seeking restitution, though he didn't have an estimate.

The Heenes twice appeared on the TV reality show "Wife Swap," including a March episode in which they discuss their approach to parenting and talk about their belief that they're the descendants of aliens.

The producer of "Wife Swap" had a show in development with the Heenes but said the deal is now off. The TLC cable network also said Heene had pitched a reality show months ago, but it passed on the offer.