Pavel Durov, the co-founder and CEO of the messaging app Telegram, was arrested at an airport in Paris Saturday after getting off his private jet, according to French media reports.

The billionaire Russian exile was arrested at around 8p.m. at Le Bourget airport by french cops after flying in from Azerbaijan, French outlet TF1 Info reported.

French authorities had issued a search warrant as part of a preliminary investigation into Durov and his encrypted messaging app, which has some 900 million users worldwide.

Law enforcement believe that Telegram’s lack of moderation and the tools it offers, such as cryptocurrencies, make it complicit in global drug trafficking, pedophilia and fraud. But the search warrant was only valid if Durov stepped foot on French soil.

“He made a blunder this evening. We don’t know why… Was this flight just a stopover? In any case, he’s in custody,” a source close to the investigation told TF1.

Durov, 39, is a Russian-born tech entrepreneur best known for founding the social networking site VK (VKontakte) and the messaging app Telegram. 

He lives in Dubai, where Telegram is based, and is also a citizen of France and the United Arab Emirates, according to Fortune.

Durov founded Telegram in 2013 with his brother Nikolai, but fled Russia in 2014 after he refused to hand over encrypted user data to Russian officials or silence communities opposing the government, which he later sold.

Durov decided to live in self-imposed exile, stating when he left that Russia was “incompatible with internet business at the moment,” according to The Sun.

He is worth an estimated $15.5 billion, according to Forbes.

Telegram emphasizes users’ privacy, which has drawn criticism from many governments for allowing militants and organized criminals to discreetly communicate.

It has also become a major source for information in the Russia-Ukraine war.

Durov has maintained that Telegram is a neutral social media platform and not a “player in geopolitics.”

He is expected to appear before a judge on Sunday on charges connected to terrorism, narcotics, complicity, fraud, money laundering, receiving stolen goods and child pornography, according to TF1.

“Pavel Durov will end up in pretrial detention, that’s for sure ,” an investigator familiar with the case told TF1.

“On his platform, he allowed an incalculable number of offenses and crimes to be committed, for which he did nothing to moderate or cooperate, ” the source added.