It should surprise no one that there are some dark, depressing and duplicitous things on the internet and much of it hides in plain sight.
On Backpage.com, which hosts classified listings for a wide variety of products and services, women promote themselves, offering an array of adult services. Some claim to be independent, others are clearly not.
Ads like these are posted for cities all around the world including major New Zealand cities and towns. Depending on the market, only a tiny fraction might be related to anything nefarious but some of these women are girls who have been abducted, recruited or seduced into a world they never wanted.
Victims of underage sex trafficking have filed a number of lawsuits against Backpage.com accusing the company of assisting in abuse by allowing pimps and human traffickers to advertise sex with minors on its website.
As part of investigations surrounding lawsuits against the company, a US Senate report last year found the website would manually remove words that indicated the person being advertised was a child, such as "little girl" and "amber alert". It would then repost the sanitised ad, the inquiry found.
Filmmaker Mary Mazzio met and spoke to a number victims to produce a documentary about the victims who found themselves for sale on the seedy website, described in the film as the "Wal-Mart of human trafficking".
Speaking to news.com.au last year she explained how many of the victims came to be posted for sex work.
"They're preyed upon online. [Sometimes] it's a new friend, normally a boyish-looking adult," she said.
"Almost every victim that I spoke with that was recruited that way; they were recruited for six months. They thought it was a first boyfriend and then the fangs came out."
It's well-known law enforcement agencies tasked with investigating trafficking crimes routinely scour sites like Backpage.com. But there's been little they could do to hold such websites accountable.
In 2016, Backpage CEO Carl Ferrer and two other co-founders were cleared of charges relating to the pimping of minors after a Californian judge ruled the operators of the classified listings site could not be held accountable for users' content.
However a new bill proposed in the US aims to take down a law that shields a wide range of online publishers from liability for content on their sites in a last-ditch effort to crack down on the harrowing trade.
If successful, it could make it easier for authorities to stifle sex trafficking crimes, at least at a major point of sale.
The bill, dubbed the Allow States and Victims to Fight Online Sex Trafficking Act (FOSTA), is set to be voted on by US politicians as early as this week and could have widespread impact on the nature of the internet and change favourite sites like Facebook, Twitter, eBay and dating websites.
Backpage.com has previously argued it is merely hosting content, not creating it, and is thus protected from liability by legislation known as the federal Communications Decency Act.
The CDA, enacted by the US in 1996, helped pave the way for the explosion of social media platforms, such as Facebook and Twitter, as well as online marketplaces including Amazon and eBay.
California Republican and sponsor of the new bill Mimi Walters said the new restrictions pertaining to a particular section of the CDA "will significantly help prosecutors crack down on websites that promote sex trafficking, while providing much-needed recourse for the thousands of men, women and children who are victims of this evil industry".
But others are concerned it will significantly hamper free speech on the internet.
Critics of the measure say the proposed legislation would undermine a basic underpinning of the internet, which enables websites to host information from third parties without liability.
Emma Llanso, of the Centre for Democracy & Technology based in the US, said the bill will result in online censorship.
"This bill jeopardises not only classified ads sites but also dating apps, discussion forums, social media sites and any other service that hosts user-generated content," she told the Associated Press.
Eric Goldman, director of the High Tech Law Institute at Santa Clara University, agreed that if the bill becomes law it could encourage website operators to censor any potentially risky content or even take a hands-off approach to show they did not "knowingly" facilitate human trafficking.
In a blog post this week, he outlined how the new legislation could ultimately backfire because of something he called the "moderator's dilemma".
"The moderator's dilemma is bad news because it encourages internet companies to dial down their content moderation efforts, potentially increasing the quantity of 'bad' content online — including, counter productively, the quantity of now-unmoderated sex trafficking promotions," he wrote.
Much of this illegal activity is taking place in plain sight, just a click away from ads for gardening utensils. But given its sordid nature and the rise of the dark web, underage sex ads have been pushed deeper into the hard-to-reach places of the internet.
In recent years, the US military's research unit tasked with developing new technologies worked to find a solution to that problem. Since as early as 2014, Darpa, or the Defence Advanced Research Projects Agency, began building something called the Memex program to help identify human trafficking on the dark web.
The premise of the Memex program is to identify content on the surface and dark web indicative of human trafficking by using sophisticated web crawler technology that systematically scrapes the internet sniffing out certain content.
Searching the dark web is especially difficult because websites are not indexed like they are on the surface web.
"Our goal is to understand the footprint of human trafficking in online spaces, whether that be the dark web or the open web," Wade Shen, a programme manager in Darpa's information innovation office, said last year.
Although the US Department of Defence praised the technology as a successful tool in the fight against online sex trafficking, without the ability to hold websites like Backpage accountable for the illegal content they host, law enforcement agencies face an even bigger uphill battle.
Barrister says prosecutors focused on messages to undermine Erin Patterson's family ties.