LOS ANGELES — Once Richard Heene admitted in court that he wrongly sent authorities on a wild goose chase across Colorado to save the son he thought was aloft in a runaway balloon, friends and supporters seemed to take off just about as fast as that balloon.

All except for one: Steven Barber, a 48-year-old filmmaker who says he still believes Heene really thought his son was in the balloon as it spun wildly through the skies on Oct. 15. He plans to prove it, Barber says, when he releases the documentary "Balloon Boy: Guilty Until Proven Innocent" later this year.

Barber has known Heene — now serving 90 days in jail after pleading guilty to falsely influencing authorities — for more than 10 years and says he has dozens of hours of film of the backyard inventor pursuing one science project after another. He compiled much of that footage, the filmmaker says, in an effort to help Heene land a TV reality show chronicling his science adventures.