United States authorities arrested a suspected dark web drug dealer as he traveled into the country from his home in France to attend the World Beard and Moustache Championships.

Gal Vallerius, a French 38-year-old with a magnificent red beard, is accused of being a drug kingpin on the dark web, acting as an administrator for Dream Market, a marketplace for illegal narcotics including cocaine, heroin and methamphetamines, counterfeit consumer goods and stolen data.

Vallerius was arrested as he landed at Atlanta international airport on 31 August, and during a border search of his laptop confirmed his identity as “OxyMonster”, the username for a Dream Market account that was not only listed as an administrator for the site but also listed prescription drugs including OxyContin and Ritalin for sale. Officials also discovered about $500,000 in bitcoins, the currency used for anonymously trading on the marketplace.

The arrest, first reported by the Miami Herald, was the culmination a multi-agency investigation that started in February 2016. As part of the investigation, Drug Enforcement Administration agents made undercover purchases of crystal meth, LSD and hydrocodone from a range of vendors on Dream Market and trawled the site to identify the usernames associated with the organising team.

“OxyMonster knowingly participated in the Dream Market conspiracy not only as a vendor, but also in a leadership and organizational role as a senior moderator and administrator,” court documents state.

Vallerius, left, with Garey Faulkner at the 2015 World Beard and Moustache Championships in Austria. Photograph: Instagram

Investigators tied the username to Vallerius’s real identity through his bitcoin transactions, some of which went to bitcoin wallets associated with his name. They then tracked down his Instagram and Twitter accounts to compare the writing style with that of OxyMonster and discovered “many similarities” including the use of the word “cheers”, frequent quotation marks and intermittent French posts, according to court documents filed in Florida.

His trip to the beard contest was Vallerius’s first time in the United States. He had registered for the “full beard 30.1-45cm” category, one of 27 at this year’s event.

Bryan Nelson, the co-founder of the Austin Facial Hair Club, which hosted this year’s championships, described the arrest as “pretty dramatic”. This year’s event had 738 competitors from 33 countries and, apart from Vallerius, the only contestants who weren’t able to attend were people from Nepal and the Middle East who had trouble getting their visas.

Although Nelson had never met Vallerius in person, he immediately recognized him when he learned of the arrest from his involvement in an app called “Beard Wars”.

Players of Beard Wars would bet chips on their own beard versus someone else’s beard and other people would vote for the best one. The person with the most votes would win the chips.

Nelson and his friend MJ Johnson would consistently rank No 1 and No 2 within the app, until a user called “Barba” came out of nowhere and started amassing loads of chips.

“You could see false accounts were getting created to make bets,” said Johnson, one of the winners at this year’s World Beard and Moustache Championships.

Within weeks, Barba had more chips than Johnson and Nelson put together.

Nelson and Johnson felt vindicated in the Beard Wars this week when they saw Vallerius’s photo in the news. It turns out that “Barba” was actually Gal Vallerius.

“As soon as I saw the story and saw he was a computer guy it all made sense,” said Johnson.

Johnson, who also met Vallerius at the 2015 championships in Austria, said that he “always seemed like a fun, carefree person”.

Regardless of his alleged crimes, both Nelson and Johnson are impressed by Vallerius’s facial hair.

“I don’t know anything about what other stuff he did, but as far as his beard goes, it’s really awesome, long and bright red,” said Johnson.

Vallerius’s arrest is the latest episode in a broader crackdown on dark web marketplaces by the US government, which previously infiltrated and shut down AlphaBay and Hansa.

Following the closure of AlphaBay and Hansa, many traders had flocked to Dream Market to continue their operations.

At a court hearing in Atlanta, Vallerius did not contest his identity and detention. He is expected to be transferred to Miami, where the complaint was filed, where he faces another conspiracy indictment that carries up to a life sentence.