FORT COLLINS, Colo. – A sheriff said Saturday that his office will file criminal charges in the case of a 6-year-old boy who vanished into the rafters of his garage while the world thought he was zooming through the sky in a flying saucer-like helium balloon.

After the boy's parents, Richard and Mayumi Heene, met with sheriff's officials for much of the afternoon, Larimer County Sheriff Jim Alderden didn’t say who would be charged or what the charges would be, but he did say the parents spoke to investigators voluntarily and weren’t under arrest.

Alderden previously said that if the balloon ordeal was a hoax, the parents could be charged with making a false report to authorities, a low-level misdemeanor.

"We were looking at Class 3 misdemeanor, which hardly seems serious enough given the circumstances," Alderden said Saturday. "We are talking to the district attorney, federal officials to see if perhaps there aren't additional federal charges that are appropriate in this circumstance."

He said deputies were seeking a search warrant for the family's home, and there would be more information at a news conference Sunday.

The Heenes were expected to speak to reporters outside their home later Saturday, after a strange day that began with Richard Heene knocking on the windows of journalists camped outside his home and promising a "big announcement." A few hours later, he did an about-face when he told reporters that they should leave questions in a cardboard box on the front doorstep.

As Heene walked away, a reporter shouted, "Can you tell us once and for all if this is a hoax?"

"Absolutely no hoax. I want your questions in the box," Heene said, waving a cardboard container before going back into his home.

A circus-like atmosphere formed outside, including men holding signs and occasionally yelling "balloon boy." One sign read, "Put balloon boy on TV: America's Most Wanted."

Other gawkers carried aluminum-foil stovetop popcorn makers that resembled the silvery balloon launched from the family's backyard Thursday, with Falcon believed to be onboard.

While Richard and Mayumi Heene were at the sheriff's office, the couple's three sons remained home, apparently being watched by sheriff's officials. Authorities wouldn't comment on what was happening.

Alderden had said that he wanted to re-interview the family after Falcon told CNN that "you said we did this for a show" when asked why he didn't come out of his hiding place. Then Falcon got sick during two separate TV interviews when asked why he hid.

The balloon was supposed to be tethered to the ground when it lifted off, and no one was supposed to be aboard. A video of the launch shows the family counting down in unison, "3, 2, 1," before Richard Heene pulls a cord, setting the balloon into the air.

"Whoa!" one of the boys exclaims. Then his father says in disbelief, "Oh, my God!" He then says to someone, "You didn't put the (expletive) tether down!" and he kicks the wood frame that had held the balloon.

Falcon's brother said he saw him inside the compartment before it took off and that's why they thought he was in there when it launched. Heene said he had yelled at Falcon before the launch for getting inside.