Anh Dung said he took down Ionechat.com after receiving emails from reporters and said the photos of the 17-year-old girl were gathered randomly from Google by a so-called image scraper. Dung said he was not aware of Parsons's story and feels guilty about what happened.
A photo of Parsons, who was taken off life support and died in April after a suicide attempt, was used on Facebook to advertise a dating website under the heading, "Find Love in Canada! Meet Canadian girls and women for friendship, dating or relationships."
Glen Canning, Rehtaeh's father, said seeing the ad was "disturbing and disgusting" and his daughter's photo should never have been used for that purpose.
Meanwhile, Carmi Levy, an independent technology analyst, said it's "shockingly easy" for a company to do just that.
"It's relatively easy for an advertiser who isn't paying attention, whether through malice or not, is irrelevant. Just to scrape that picture off the internet, paste it into an advertisement and off you go," he told CBC News.
"It shows that there's no due diligence, no one is minding the store to make sure that the pictures that are in fact being included here are in fact appropriate for use."
Facebook apologized Tuesday after multiple complaints and said the ad was a "gross violation" of the company's policies and has been removed. The social media website said Ionechat.com has been banned from advertising on its website.
"We apologize for any harm this has caused," a spokesperson for Facebook wrote in a statement.
Ionechat.com was an affiliate marketer for the dating website company called be2, and was responsible for pushing traffic to be2 in return for cash. Annabel Marshall, a spokeswoman for be2, said Ionechat.com violated a company policy that states photos can only be used with permission for advertising.
"It was utterly inappropriate for Ionechat.com to use Rehtaeh Parsons's image in this way and our sympathies go out to the many Canadians who must have been distressed by seeing the advertisement," Marshall told CBC News in an emailed statement.
"The behaviour of the company providing Ionechat.com was careless in the extreme and we are considering our own legal options in regards to the damage done to the be2 brand."
Parsons' story is well-known to Canadians after the details of her suicide came to light. Her parents claimed she was sexually assaulted at a party when she was 15 years old and then relentlessly bullied, with a photo of the assault spread online.
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Levy points out Facebook has explained the team it has in place is to monitor complaints after the fact.
"They need to get into the process further upstream so that this never happens again at all," he said.
"The takeaway message is you're going to want to control what goes online because once it gets online there's no pulling it back. Anyone, anywhere can grab it off of the screen and use it as they wish and your ability to find it after the fact, it depends on someone bumping into it, happenstance online. Losing control is way too easy."
Canning said blocking the company was the only acceptable response.
"What a thing for a parent to see. Especially because Rehtaeh is the victim of a sexual assault and they have her on a dating website. Not only that, she's also a minor. What does that say?" he said.
"In my heart it's just inexcusable. There's just no way I would accept an excuse that this was just some kind of a glitch."