Prof. Robert Currie of Dalhousie University in Halifax said companies are increasingly using automated programs that rip photos from websites, and it was only a matter of time before the now-ubiquitous image of the 17-year-old girl wound up somewhere it shouldn't have.
"This is how technology works and it's another example of how little control anyone has over any image once it gets out into the Internet sphere," said Currie, director of the university's Law and Technology Institute.
"It really seems to me to be an unfortunate accident that is causing a lot of grief and heartbreak to the Parsons family and others who loved this girl and who were disturbed by this case. But it's just the kind of thing that is going to happen."
The ads for Ionechat.com featured pictures of Parsons under the heading, "Find Love in Canada! Meet Canadian girls and women for friendship, dating or relationships."
Parsons hanged herself in April and was taken off life-support days later. Her family says her death was brought on by months of bullying following an alleged sexual assault. Her story has generated headlines around the globe, and a search of her name in Google Images generates hundreds of photos from blogs and news websites.
The administrator of Ionechat.com, Anh Dung, said the photos used in the ads were a mistake and taken randomly from Google by a so-called image scraper.
"I'm a foreigner, so I didn't even know her name and the story ... so I didn't know it was the victim's photo," Dung wrote in an email, adding that he immediately took the website down after receiving emails from reporters.
"I feel so guilty, I sincerely apologize," he continued. "I'm so stressed right now."
Parsons's father, Glen Canning, said the photos — many of which are posted on a Facebook page in memory of the teenager — should never have been used.
"For something like that to happen to Rehtaeh, given the circumstances of her death and the grief we've gone through, it was pretty disturbing and disgusting to see something like that," he said in an interview.
"It's our image. It belongs to Rehtaeh's family. Just to lift it off and start using it like that is very thoughtless."
Anatoliy Gruzd, a social media expert at Dalhousie, said he believes image scraping raises ethical questions even if the dating website didn't mean any harm.
"It clearly would be unethical to automatically scrape pictures where you don't have permission and use it for commercial purposes," said Gruzd, director of the school's social media lab and a professor of information management.
"But unfortunately, for those companies or organizations that are scraping those images automatically, it's hard to train the algorithm to recognize what pictures are OK to scrape and what pictures are not."
Andrew Ennals, a copy writer in Toronto, said he alerted Facebook to the ad when he spotted it on his Facebook page Tuesday afternoon. Ennals said he noticed the ad on the page's right-hand column and was stunned to see the picture of Parsons, which had been used widely in the media after her death.
"I don't normally notice those (ads), but I thought the picture looked really familiar," he said in an interview Tuesday.
"So I just did some quick screen grabs — I was just completely stunned that this could actually happen."
Ennals tweeted the screen grabs and contacted Facebook.
Facebook apologized for the ads, saying they were a "gross violation" of the company's policies and have been removed. It also said Ionechat.com has been banned from advertising on its website.
Canning said he was pleased to see Facebook take the measures it did.
"I think banning the Ionechat.com company was the right move to make," he said. "It's hard to say what can be done but I think Facebook removed it fast, and I appreciate that and they apologized for it which is good."
Currie said the best recourse for someone whose snapshots wind up in an online ad is to contact the company directly and ask to have the photo removed.
He said the law surrounding online privacy is murky and there are limited abilities for people to take legal action if they believe their image is being misused.
"If you are going to be involved in social media, you really do need to adjust your notions of what you think privacy is."