MONTREAL -- The family of a late Canadian man accused of masterminding the world's leading "darknet" internet marketplace said Friday they're having a hard time believing he was a hardened criminal.

Alexandre Cazes, 25, from Trois-Rivieres, Que. is accused of creating AlphaBay, an online marketplace that authorities say traded in illegal drugs, firearms and counterfeit goods.

Arrested by police in Thailand in early July, officials have said Cazes hanged himself while in their custody on July 12, just before a scheduled court hearing.

Authorities said they have sought the forfeiture of Cazes' properties in Thailand, bank accounts and four vehicles, including a Lamborghini and a Porsche and said he amassed a fortune of $23 million with the creation of AlphaBay in 2014.

But Cazes' family is disputing the U.S. authorities portrayal of the Quebecer as a criminal mastermind.

"If what the FBI says is totally true, well, that's not the Alexandre Cazes we know," his stepmother Kathy Gauthier told The Canadian Press in a Facebook private message.

"(If it's true) we'll still love him and forgive him," she said.

In a series of messages published on social media, Gauthier described Cazes as an "introverted and peaceful" young man who amassed a fortune by investing in digital currencies.

She questioned whether authorities were exaggerating his alleged role because they needed someone to blame.

"Now that Alex is dead it's hard to have information so why not put all the counts on Alex's back," she wrote Friday.

On Thursday, U.S. Justice Department officials gave details of the global police operation that brought down Cazes.

According to the indictment, he accidentally broadcast his personal Hotmail address in welcome messages sent to new users. And when he was tracked down and arrested in Thailand, Cazes was logged into the AlphaBay website as its administrator, allowing investigators access to passwords and other information.

The site went offline July 5 after Cazes's arrest in Thailand.

In an interview last week with local radio station 106.9 FM, Cazes' father said the 25-year-old had no previous history with the law.

"He never had a criminal record," Martin Cazes told the station. "He never smoked a cigarette, never took drugs."

He described his son as a "computer genius" who built websites and computer programs through EBX Technologies, a company he founded in 2009.

Philippe Gravel, investigator with Integrated Technological Crime Unit of the RCMP, said the force became involved in the case in January, when the FBI and DEA asked it to help locate Cazes in Quebec.

"We started a parallel investigation at that time, in order to build a profile on him in the province of Quebec," Gravel said. "We don't exclude there being other arrests in this case."

Gravel said Cazes' arrest will make those who buy weapons and drugs on the internet think twice.

"Our first goal was to shut down the site," he said. "Our second was to hurt the credibility of the site and the confidence of people using this type of service, knowing at any time these sites can be seized or even operated by police."

By the time authorities closed in on July 5, Cazes had amassed a $23 million fortune as the site's creator and administrator, court documents show.

An acquaintance who knew Cazes when he was a student in Trois-Rivieres remembers him as someone who was friendly, helpful and hard-working but ambitious.

"He really wanted to have his own business, that was his dream," said the friend, who did not wish to give her name.

Nevethertheless, she said she wasn't entirely surprised by the allegations against him.

"He was always looking for good business opportunities, I wonder if maybe he took the easy road," she said.

Cazes' neighbours in Thailand painted a picture of a young man who displayed flashes of ostentation but otherwise seemed unassuming.

"He was with his girlfriend," said a neighbour, Hassanupong Pootrakulchote told The Associated Press. "Around New Year's or Christmas I saw some of his friends come over and they would have a little party. There were Thai people, some of them were his girlfriend's relatives ... Other than that it's mostly quiet, nothing flashy or anything."

Nothing except those expensive cars, which were completely out of place in the neighbourhood where homes cost less than $120,000.

"Why does he have a Lamborghini? Why does he have a Porsche or Mini Cooper?" said Hassanupong, who said he thought Cazes was in the hotel business.

In Washington on Thursday, U.S. Attorney General Jeff Sessions said the operation to shut down AlphaBay was the largest darknet marketplace takedown in history.

Darknet vendors are "pouring fuel on the fire of the national drug epidemic," he said, specifically citing cases of two U.S. teenagers killed this year, one a 13-year-old Utah boy, by overdoses of synthetic opioids purchased on AlphaBay.

With files from The Associated Press and Giuseppe Valiante in Montreal.