Sheriff Alderden said that at first the parents' acting abilities had made them appear credible to the police.
But it had become clear when the son referred to his hiding as part of "a show" during a television interview that they were not telling the truth.
Sheriff Alderden said the authorities were investigating whether anyone else may have been involved, including a media outlet that may have been in on the hoax.
"We certainly know that there's a conspiracy between the husband and wife, you've probably seen some of the e-mails and some of the things on the internet suggesting that there may be other conspirators," he told reporters.
Investigators have said they want to question Robert Thomas, an associate of Mr Heene's in Denver, who provided the website Gawker.com with e-mail exchanges from several months ago in which he and Mr Heene talk about a possible balloon stunt to promote a proposed reality TV show.
Police have searched the house of Richard and Mayumi Heene for evidence that the family was hoping to use the incident to obtain a lucrative contract for such a show.
The family has made previous appearances on a US reality show, Wife Swap.
US news networks devoted hours of live coverage to the drama on Thursday after it was reported the boy might be in a balloon floating high over Colorado.
The sheriff accused the Heenes of staging a publicity stunt
Denver International Airport was temporarily shut down during the incident.
When the balloon landed in fields there was no trace of him, prompting a major ground search and further fears for his safety.
The sheriff said the police may seek compensation for the time wasted.
He did not give an estimate, though the Associated Press news agency said the cost of two police helicopters sent out on a rescue mission was $14,500 (£8,900).
The boy, his two brothers and his parents gave numerous TV interviews late on Thursday and early Friday. Falcon was twice sick on camera.
The desperate desire for celebrity - of any sort - has long been a dominant feature of our culture, no matter how ignoble or notorious the acts people may have to pull off for their 15 minutes of fame... But, if the police are right, the culture may have reached a new low in which parents involve their children in huge lies with huge consequences.
If this were a game of Texas hold 'em, the Heene family would have just gone all in... In this hand of poker, the winner collects the most face time on television and the Internet. But while the attention is satisfying, the Heenes must think the ultimate jackpot is the lucrative book deal or movie rights or reality TV series. They're after the big money, and they're willing to gamble not only with their individual freedom and finances, but also with the emotional future of their young children.
Scott Collins and Nicholas Riccardi, of the Los Angeles Times, look at the
Children's advocates warn that reality-TV producers and news organizations are exploiting children from exotic backgrounds for higher ratings. In the 'balloon boy' case, TV news was rewarded for sticking with the story: As the drama unfolded Thursday afternoon, the cable news networks logged ratings roughly double their usual averages, according to the Nielsen Co.
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