"This has not been an easy case to decide," he said when he found Michael Marin, 64, not guilty of the charges, which included three counts of sexual assault, as well as counts of sexual interference and sexual touching.
Gareau said the complainant's evidence simply raised "too many red flags" to let him conclude he was sure of Marin's guilt.
"I am not saying that I disbelieve the complainant's evidence or that I have concluded she has misled or lied to the court."
But her evidence didn't rise to the standard where he could conclude, beyond a reasonable doubt, that the Crown had established all of the essential elements of the offences, he said.
There are some aspects of her testimony that "defy logic, seem incredible, and raise a reasonable doubt."
His decision follows a nine-day trial in July, where the court just heard from the complainant, the only witness called by prosecutor David Kirk.
Marin didn't testify, and his lawyer Bruce Willson didn't call any evidence.
The offences were alleged to have occurred over a number of years, beginning when the complainant was young and continuing for years after she became an adult.
A publication ban prohibits reporting any information that could identify the complainant.
She testified that Marin first touched and kissed her when she was a pre-teen, and it slowly progressed to sexual acts.
In his 12-page decision, which he read in court, Gareau said, despite the red flags, there also were areas where the woman had an opportunity to fabricate or embellish evidence, and she did not do so.
"It is fair to say" that the red flags cast doubt on the believability of her evidence, but there also were aspects of her testimony that led him to believe that she was "being truthful and forthright in her version of the events."
When assessing the woman's credibility, the judge said he considered her demeanor in the witness box.
The complainant's reluctance to testify and the difficulty she had giving her evidence to the court were clear from the outset, he said, noting she had asked for frequent breaks that often turned into lengthy pauses in the proceedings.
During cross-examination, when the defence suggested to the woman that her evidence was fabricated as "payback," she firmly replied, "No, it's not. I don't want to be sitting up here. I just don't want him to hurt anyone else."
Gareau said he accepted that she didn't want to be in the witness box, and that it was difficult for her to testify, which likely wouldn't be the case if someone was trying to extract revenge.
"One would expect a revenge seeker to relish giving evidence a great deal more than the complainant while giving her evidence."
While being questioned by the Crown, the complainant portrayed herself as someone who was easily manipulated by the accused and his sexual demands, Gareau said.
In cross-examination, many of her answers about her relationships with other people painted a different picture, indicating a strong-willed individual who didn't bend to pressure or was able to get others to do what she wanted, he said.
In considering the only evidence he heard -- the complainant's testimony -- the judge said the court must bear in mind the principle of reasonable doubt, "a cornerstone in the criminal justice system in Canada."
Gareau referred to the reasonable doubt instructions that a trial judge gives to jurors before they begin their deliberations.
The instructions conclude that "if, at the end of the case, based on all of the evidence or the lack of evidence, you are not sure that the accused committed the offence, you should find him not guilty of it."
EDITOR'S NOTE: SooToday does permit comments on court stories
More local news
Browse local flyers
Weather forecast
Find local deals
View local webcams
Verified Commenter, please