Andrew Jarecki is the very young, very rich founder of Moviefone.

When he set out to make his first film, he chose as his subject New York's number one birthday clown, Silly Billy. Also known as David Friedman, he was the subject of a 4,000-word New Yorker profile by Susan Orlean, author of The Orchid Thief.

Jareki lucked out. While researching his story, he found material Orlean and others had overlooked. He was helped by the fact that Friedman and his family were compulsive chroniclers of their own twisted lives. In the process, Jarecki ended up with an award-winning documentary that works simultaneously on several levels.

For one thing, it is reality television before the phrase was even coined. But whereas, say, The Osbornes relies on Ozzy's booze- and drug-addled personality, the Friedmans have a far more compelling reason to be onscreen -- its paterfamilias had problems darker than Ozzy Osborne or Archie Bunker or Homer Simpson.

On another level, Capturing The Friedmans is a piece of first-rate investigative journalism. It looks at a decades-old case of paedophilia that splintered a family, incarcerated two if its members, and left nothing but shades of ambiguity and human wreckage in its wake.

David Friedman's father Arnold was an award-winning teacher, a pianist, and a computer nerd. In 1984, authorities noticed he had ordered a child porn magazine from the Netherlands. In a three-year sting operation, a federal investigator posing as a postal clerk pretended to be a paedophiliac and begged Friedman to send him porn. Friedman did and the feds raided his home, breaking down the door with a battering ram.

What happened next defies logic and the imagination. Through a combination of public hysteria and law-enforcement wrongdoing, Arnold Friedman and his youngest son Jesse ended up in jail, accused of child molestation. Jesse, only 19 at the time, would spend 13 years inside; Arnold would die there, an apparent suicide.

As Jarecki's film reveals, the sex crimes unit that investigated the case used methods that would not stand up in court today. Overcome by what journalist Debbie Nathan, a talking head in Jarecki's film, describes as 'cultural hysteria', investigators used everything from hypnosis to threats and intimidation of witnesses to get the Friedmans indicted as quickly as possible.

Friedman was convinced that a plea of guilty would save his son, but his sacrifice became pointless. Jesse received the longest possible jail term. Arnold then took an overdose of prescription medication knowing his son would receive a $250,000 insurance payoff.

The astonishing aspect of Capturing The Friedmans is the amount of footage of family crises, goofing around, and tense dinners that are captured on camera. Sometimes it is difficult to tell which camera it is. Is it David Friedman's Super 8, preternaturally active, filming everything his family said and did? Or is it Jarecki, attempting to be as ambiguous and non-committal as possible?

Then there are the spooky scenes -- Jesse clowning outside the courtroom just before he is sentenced to 13 years; Arnold's little sister, ballet dancing in flickering black and white, just before her death at the age of 5 from blood poisoning; Arnold's brother, interviewed throughout the film, revealed to have been molested by Arnold as a boy, now living in Oregon with his gay partner.

Jarecki's film won Best American Documentary at the Sundance festival. It is a unique document, not only of the tragic Great Neck, Long Island, family it chronicles, but also of an American decade when greed was good and mullets were in.

It was a time when computers were still an unknown quantity. The pictures of the computers Arnold Friedman taught on have the vintage quality of sepia. They are ancient instruments far removed from the sleek machines of today.

Though the film documents a long-gone time, the witch-hunting and hysteria it is full of are only too familiar.