The investigation into Telegram boss Pavel Durov, initiated by a small cybercrime unit within the Paris prosecutor’s office and led by Johanna Brousse, has sent ripples through the global tech industry. The arrest of Durov last Saturday marks a significant shift in how global authorities may handle tech executives reluctant to control illegal content on their platforms.

Durov’s arrest underscores the determination of the J3 cybercrime unit, but the true test lies in whether Brousse can secure a conviction based on a largely untested legal argument. In a groundbreaking move, prosecutors argue that Durov is responsible for the alleged illicit activities on his platform, placing him under formal investigation on organized crime charges. He is suspected of complicity in operating an online platform that facilitates the posting of child abuse images, drug trafficking, and fraud.

Durov’s lawyer has dismissed these allegations as “absurd,” stating that the app complies with European laws. Being placed under formal investigation in France does not imply guilt or necessarily lead to a trial; it indicates that judges believe there is sufficient evidence to continue the probe. Investigations can span years before reaching trial or being dropped. Durov is currently out on bail but prohibited from leaving France.

Brousse’s unit began investigating Durov earlier this year after observing his app being used for numerous alleged crimes and experiencing a “near-total lack of response from Telegram to judicial requests,” according to Paris Prosecutor Laure Beccuau. Brousse declined to comment.

In a January interview, Brousse mentioned that her office was handling an increasing number of investigations involving Telegram and rival messaging app Discord, noting that combating crime on these platforms was “one of my battles.” Discord’s CEO, Jason Citron, did not respond to a request for comment.

Brousse’s J3 cybercrime unit, despite being France’s most significant, is small, with just five prosecutors compared to Switzerland’s 55-60 cybercrime prosecutors. With limited resources, they “prioritize the most serious crimes,” Brousse told Le Figaro last year.

In a 2022 podcast, Brousse emphasized the need to be tough so that cybercriminals believe they will face severe consequences if they target France. “We want people to be prosecuted, either in their country or in France through arrest warrants,” she said. Her office often handles “extremely sensitive cases,” where legal and geopolitical issues intersect.

Patrick Perrot, who coordinates AI-assisted probes at the French gendarmerie, highlighted the J3’s innovative approach in pursuing cases that set international precedents. “This shows that you can’t do whatever you want with these platforms,” he told Reuters. “The challenge of regulation is essential as these platforms continue to multiply.”

Brousse has led the J3 since 2020, overseeing some of France’s most critical and controversial cybercrime cases. In late 2020, the J3 took charge of the Sky ECC probe, an encrypted communications service used by criminals. Following server hacks by French, Dutch, and Belgian police, French prosecutors gained jurisdiction over many resulting investigations.

More than 6,500 arrests have occurred since the 2020 Encrochat takedown, with legal challenges ongoing across Europe. Paul Krusky, the Canadian Encrochat boss, was extradited to France in February and awaits trial. Lawyers for Sky ECC’s Jean-François Eap contest his French arrest warrant, asserting his innocence.

Two French lawyers working on Sky ECC and Encrochat cases told Reuters that these earlier investigations provided prosecutors with the ambition and blueprint to target Durov. Robin Binsard, who has fought Encrochat cases in France’s top court, said prosecutors must prove that Durov knew and approved of the criminality on the app, calling their argument “questionable.” He added that non-compliance with law enforcement requests “does not automatically make one an accomplice to a criminal project.”

Binsard noted that France is targeting encrypted messaging providers, and other operators, such as Signal, should ensure compliance with French regulations to avoid legal action. Signal did not immediately respond to a request for comment.

A source at the Paris prosecutor’s office clarified that the Sky ECC probe is unrelated to the Telegram investigation.