TORONTO - The story behind decades-old allegations of systemic sexual abuse in eastern Ontario will suffer serious gaps, despite a full public inquiry, if the former police officer who exposed the tale doesn't testify, those close to the inquiry said Thursday.

Perry Dunlop fought for years to bring allegations of a pedophile ring in Cornwall, Ont., before the scrutiny of the justice system, but now says he's lost faith in the system and won't testify - despite a court order compelling him to do so.

Dunlop's stance, given the key role he's played in what has been a painful episode in the city's history, has left commission counsel and others baffled as to what good can come of his refusal.

"I just don't know how it furthers the cause of victims, and us as a society, to not hear his evidence," said John Swales, who served as a liaison of sorts between alleged victims and a London, Ont., law firm at the outset of the inquiry.

"The frustrating part for me is that we're missing the opportunity to hear his words."

Dunlop has already been found in contempt for refusing to testify last year and is facing a judge's order to appear before the inquiry when hearings resume Monday.

Earlier this week, he told The Canadian Press the "judicial system is broken" and that he won't travel from his home in Duncan, B.C., to Cornwall to give evidence before the inquiry, which has cost some $12 million to date.

"Ironically, that's exactly what we're looking at," said Peter Engelmann, lead commission counsel. "We're looking at whether there are deficiencies in the justice system."

The inquiry's mandate is to look into how authorities responded to the dozens of accusations that men had sexually abused children over decades.

"We're trying to tell as much as this story as we can and there will be a gap (without Dunlop's testimony)," Engelmann said.

"He and many others called for this inquiry . . . Clearly he was an important witness."

While Engelmann expressed personal disappointment, he added if Dunlop does not appear Monday it will be a "disappointment for many, many people here in the Cornwall area" who feel strongly one way or another about Dunlop and his actions.

"Everybody has an opinion of Perry Dunlop here," he said.

"I think it's just disappointing that they're not going to see him be examined and cross-examined on many of the things that he did and many of the things that he said."

Conducting his own off-hours investigation in the early 1990s, Dunlop led a charge that saw prominent members of the Cornwall region's Roman Catholic clergy, and other community leaders, accused of being part of a pedophile ring.

Dunlop also brought to light allegations of a cover-up by the Cornwall police service.

Last June, Ron Leroux appeared before the inquiry and admitted stories about witnessing a group of prominent area men participating in a bizarre sexual ritual with young boys involving candles and robes were false.

"Many of the statements were made in the presence of Perry Dunlop," said John Callaghan, lawyer for the Cornwall police.

"I would have thought that Perry Dunlop would have wanted to come forward to explain his role."

In August 2001, Ontario Provincial Police ended a four-year probe of the alleged ring, dubbed Project Truth, concluding the allegations were baseless.

A total of 114 charges were laid against 15 high-profile men in the 1990s, but the courts ultimately convicted just one man who had no connection to the alleged sex ring.

The allegations of a sex ring, some of which dated back to the 1960s, persisted until a public inquiry was called in 2005.

Dunlop's refusal now to testify will leave a "void" in the inquiry's work that can only undermine the testimony of alleged victims who have already come before the inquiry, said Swales.

"It does concern me that all of the people that have come forward so far in the inquiry, with the intentions and hopes of achieving some results, their evidence would be enhanced by having Perry participate in the inquiry," he said.

If Dunlop holds true to his word and fails to appear, the commission will turn the matter over to the courts.

Dunlop has said he's prepared to face the consequences if he's arrested.