In the complaint, Homeland Security special agent Aaron McLellan reveals how he posed as three paedophile personalities on an unnamed website and social media platforms Wickr and kik to catch self-described ''perv'' Quinn.
One of the pair's first exchanges started like this: "Hello young man," the undercover agent said. "An Aussie aye? I have run across a couple of Aussie pervs on here recently.
"I guess the Aussies are waking from the winter slumber and looking to play. Ha Ha Ha... I think I might be ready for another round of fun. If you understand what I'm saying."
Quinn enthusiastically replied: "Yep, an Aussie fella here - this is a great site to meet our fellow pervs and good to hear there's a few of us Down Under.
"I'm awake and very keen for some hot action."
For weeks, Quinn would deluge the three officers masquerading as paedophiles with his stomach-churning fantasies - right up until the day he was arrested.
How 'Mick' fell for the police trap
An accomplished university-educated geneticist who worked for one of Melbourne's top IVF clinics, Quinn's sinister intentions first came to the attention of American authorities in early May.
A veteran investigator of seven years, Immigration and Customs Enforcement agent McLellan was investigating online groups where ''members expressed their sexual interest of children'', he said in his deposition.
Using an account seized by police, he found a recent post by a man written under the username "Mick".
Mick announced to the group he was travelling to Los Angeles from Australia at the end of the month.
So under the guise of a paedophile, the special agent sent him a message asking what Mick was looking for.
"I'd like to meet up with a dad who shares his yng [young] ones," the sportsman replied.
He said his favourites were boys aged between 5 and 10 years old. So the agent invited him to join a "group of us here" who "get together".
"I have hookups for certain activities," the agent said. "There's a place I can take you to enjoy a yng one."
Quinn, who was travelling with friends, replied: "I'd really appreciate that!!!"
He would say he was interested in meeting the three paedophiles - if they could deliver "the goods".
During the conversation on May 6, the agent alleged Quinn said he wanted to meet "other pervs" in the United States, agreed to pay $250 to molest a boy, and suggested they do it together.
When the "paedophile" told Quinn about how he knew a man who had let him abuse a 6-year-old, Quinn replied: "Nice! That's perfect.
"Who's the guy? Would love to share one with you mate."
According to a transcript in the complaint, the fake paedophile replied: "Haha. What I was hoping but didn't want to come across as a pushy american".
"I like catching up with older experienced pervs - they've got good profiles," Quinn confessed.
The criminal complaint said Quinn then got in touch with the two other paedophiles in the ring - both played by the special agent.
Speaking to the chief paedophile ring organiser, Quinn lavished praise on one of fake profiles he had been speaking to.
Over the course of their conversations, he laid out his travel plans to the US in detail: dates, times and an itinerary of where he was staying.
"I'm definitely keen to join in. I'm in Australia. I'm visiting LA, Nashville and NYC," he said in one conversation tendered in court.
The agent said: "Good to hear. We always like to welcome others to the group... What date you wanted to party on while here?
"You pick. We perv whenever."
Nerves, before catching an Uber to his arrest
But the day before he flew to LA, Quinn got worried, according to the complaint. He asked if he could meet up with the paedophiles and ''party'' beforehand.
"The only reason why I'd want to party is to know you're not cops," he said in an instant message. "Have a pipe and show our c**** - something like that."
The agent replied: "Lol. I get you. But we aren't police."
He started asking about the specifics of the arrangement, revealing he was staying in a home in Hollywood Hills with friends.
The agent asked: "Are the other dudes coming or hust [sic] you playing?"
Quinn replied: "lol lol just me mate - I wish they were".
But the investigators had already figured Quinn out. Intelligence officers had connected one of his usernames with the Melbourne man's Facebook account.
They found him and all his friends on Qantas Flight 19 passenger manifest, flying from Melbourne to Los Angeles, the agent testified.
The group checked in on Facebook as flying to LA on May 19, the day Quinn had told the agent he was flying out.
Two days after he landed in California, Quinn jumped in an Uber and was dropped off at a preplanned hotel room.
He met three agents who were posing as the respective paedophiles.
According to the complaint, they group had a few drinks.
Quinn sipped beer and the agents drank bourbon. Cartoon Network was on in the background and Quinn chomped into a Toy Story-themed cupcake.
The agent said in his deposition: "I told him that he would always be nervous and excitement, but that there was good stuff coming."
A fake pimp entered the room. He said: "Money time."
Quinn handed the pimp $260, "clearly remembering the previous discussions" about paying to have sex with a 6-year-old.
After he handed him the money, police came into the room, arresting everyone - "including the undercover agents".
They seized Quinn's wallet and a camera he brought along with film and a tripod-like apparatus.
Quinn struck a plea deal with prosecutors last month.
US Attorney Eileen Decker told reporters officials had ensured "no child was put in harm's way and that Mr Quinn would face severe consequences for his conduct."
He will be sentenced in October and faces up to 13 years behind bars.
