The "balloon boy" parents in Fort Collins, Colorado, concocted the stunt to market themselves for a television show, Larimer Country Sheriff Department said Sunday.

Larimer County Sheriff Jim Alderden said at a press conference that while police were searching for the boy, Falcom Heene Thursday, the boy may not have been hiding in the rafters of the family's garage. He may have been two blocks down the road playing on the swing in the city park.

Six-year-old Falcon Heene smiles as he is surrounded by reporters on the lawn of his house in Fort Collins, Colorado Oct. 15, 2009. [Xinhua]

So far Larimer County Sheriff Department has not filed any criminal charges against the parents, Richard and Mayumi Heene, who falsely reported to the police that their 6-year-old son was inside a flying balloon. Nor the parents have been arrested.

But Alderden said he would recommend charges of conspiracy, contributing to the delinquency of a minor, making a false report to police and attempting to influence a public servant.

Each of the serious charges against the parents would carry a maximum sentence of six years in prison and a fine of 500,000 dollars if convicted.

Richard Heene (L) reacts as he holds his son six-year-old Falcon Heene outside their house in Fort Collins, Colorado Oct. 15, 2009. [Xinhua]

According to the sheriff, all three of the Heenes' sons knew of the Thursday hoax, but they were unlikely to face charges because of their ages. Their oldest son is 10.

Alderden called the whole event "a hoax" and a "publicity stunt".

The boy's mother has appeared on the reality TV show Wife Swap. In an interview on CNN on Thursday, when asked by his father Heene why he didn't come out of the attic when his name was repeatedly called, the boy said: "You guys said that, hmm, we did this for the show."

The Heene family is pictured in this undated publicity photograph from the ABC reality series "Wife Swap". Shown are Richard Heene, his wife Mayumi and their sons Bradford, Falcon (C) and Ryo. [Xinhua]

Alderden said that "it became very clear to us at that point that they were lying."

"Needless to say, they put on a very good show for us, and we bought it," he added.

Six-year-old Falcon Heene squints up at a news helicopter hovering over his house in Fort Collins, Colorado Oct. 15, 2009. [Xinhua]