French prosecutors have released Telegram CEO Pavel Durov after four days of questioning regarding allegations of illegal activities on the platform.

Durov was detained upon arriving at a Paris-area airport on Saturday, sparking a debate over the responsibilities of app providers and the balance between free speech and law enforcement.

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The Paris prosecutor's office announced that the investigating judge decided to end Durov's police detention. He is expected to appear in court, where he may face potential charges. The allegations against Durov, a French citizen, include using his platform for distributing child sexual abuse material, drug trafficking, fraud, and incitement to organized crime.

Telegram is also accused of failing to provide requested information or documents to investigators as required by law. French authorities have issued an arrest warrant for Nikolai Durov, Pavel’s brother and co-founder of Telegram, with both brothers facing arrest warrants since March.

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The Paris prosecutor’s office declined to comment on the arrest warrants due to the ongoing investigation's confidentiality. Currently, Pavel Durov is the only individual being questioned in the case.

This situation highlights the strained relationship between Telegram, which has about a billion users, and governments. An official investigation in France does not automatically imply guilt or a trial but indicates that judges believe there is sufficient evidence to warrant further investigation. The probe could continue for years before a decision is made on whether to proceed with charges or close the case.