VICTORIA — A tip to an Alberta missing children's agency has led to the arrest of a Victoria woman who had been hiding here in plain sight with the daughter she is accused of abducting 18 years ago.

Patricia Joan O'Byrne, 53, was arrested peacefully at her Howard Street home at 8 a.m. on Thursday by Victoria police, who were working with Toronto Police Services to solve a parental abduction case reported on May 29, 1993.

It's the longest outstanding unsolved parental abduction case that Christy Dzikowicz, the director of missing children's services at the Canadian Centre for Child Protection, knows of in Canada.

Astounded neighbours and provincial government colleagues knew O'Byrne as Pamela Whelan, a public information officer for the provincial government at several ministries, a friendly neighbour and an active member of her daughter's school community.

Sigourney Teresa Chisholm, the child her father Joe last saw when she was 20 months old, was known to all as Thea Whelan, valedictorian of her 2009 graduating class from Victoria High School, honour student and well-liked athlete.

On Thursday, she was told her father had been looking for her for 18 years. It's not known what her mother had told her about her father. The couple lived in Toronto, had separated, and had joint custody of their baby when the mother and daughter disappeared.

At the same time her mother was being arrested at the tidy bungalow she bought in 2005, Thea Whelan was being told about her family situation by Toronto police and counsellors from the Canadian Centre for Child Protection, Victoria police deputy chief John Ducker said.

Thea has lived in Ontario for the past year, neighbours say, and is believed to be attending university, although they didn't know where.

"I cannot begin to comprehend the magnitude of what this young woman has just learned," Ducker said.

Neither can her father, Joe Chisholm, even though he has "been dreaming of this day for 18 years." Chisholm, a Toronto musician and financial adviser, said Friday that he will wait for his daughter to contact him when she is ready.

"I'm thrilled we've found her safe but I don't think we're at a Hollywood ending," Chisholm said. "My daughter's mother has been arrested. My daughter has a lot to take in and we'll wait until she's ready. It's not about my needs, it's about hers."

He has little interest in the criminal charge of abduction in contravention of a custody order that Whelan will face Monday in Toronto's College Park courthouse.

"I'm not invested in that. I don't see how it benefits my daughter."

Dzikowicz said it is completely Thea Whelan's choice when or if she has contact with her large family in Ontario.

"She'll have supports around her but she will make her own decision," Dzikowicz said. "We are obviously happy when there's a resolution to a case, but it's hard to be joyful when we know how much impact this has on everybody."

There was nothing out of the ordinary about the Whelans, say neighbours who swapped house keys with them, mowed lawns and had barbecues.

"I feel sorry for everyone involved," said neighbour Debbie Kennell. "I'd like Thea and Pam to know that we're here for you, no matter what's happened."

kwestad@timescolonist

cjwilson@timescolonist.com