Convicted pedophile Dennis Raymond Ferguson will walk free after a Brisbane judge today ruled he could not receive a fair trial due to "adverse publicity".

Judge Hugh Botting decided in Brisbane's District Court this afternoon that Ferguson, 60, would have charges against him permanently stayed.

Ferguson has been in jail since November 2005 after he was accused of sexually molesting a five-year-old girl.

He originally applied for a permanent stay of the charges last year but his application was dismissed by Judge Gary Forno last August.

Ferguson had been charged in November 2005 with molesting two girls, then aged four and five, but one of the charges was dropped in April this year when a judge found there was insufficient evidence against him.

Judge Botting said today that he didn't believe every member of a jury would be able to be "dispassionate" in considering Ferguson's case due to significant adverse publicity about his past convictions.

A third related charge was also thrown out today.

"In my view the application for a stay should be granted," Judge Botting said.

"I have formed the view that the accused cannot receive a fair trial."

Judge Botting said that the Crown case against Mr Ferguson was "tenuous" but even if he had been convicted, the time he had spent in custody since his arrest more than two-and-a-half-years ago would exceed any jail sentence ordered. Ferguson has previously served time for child sex offences. He was sentenced to 14 years jail in 1988 for sexually abusing three children in a Brisbane hotel room. He had been out of jail for about two years before he was arrested on the charges that were dismissed today.