Washington  - Colorado justice officials said Saturday that criminal charges are expected to be filed against one or both of the parents in the case of the experimental balloon thought to have carried away a six-year-old boy.

"We anticipate criminal charges will be filed sometime in the near future," Jim Alderden, the sheriff of Larimer County, told CNN.

The father of the boy, Richard Heene, has denied that the incident on Thursday had been a publicity stunt. Officials and media aircraft chased the helium-filled balloon for more than an hour before it landed, only to find the child, Falcon, was no longer on board.

After rising fears Falcon had fallen out, he was found hiding in a box in the attic apparently scared of getting a scolding from his dad. He had never been on board.

The large balloon had been anchored in the Heene's backyard.

Colorado's 9News. com reported that one or both of the parents could face charges, most likely of a misdemeanor nature.

But given the seriousness of the case, local officials were also consulting with the Federal Aviation Administration regarding possible federal charges.

Alderden made the announcement late Saturday after summoning both parents to the sheriff's office for another round of questioning on Saturday.

Alderden said there was "significant progress" after the second round of interviews, 9News. com reported.

Alderden is expected to hold a press conference at 1700 GMT Sunday with further details.

Heene and has family have participated in TV reality shows and there were questions about whether he was trying to capture attention for future press and media involvement. (dpa)