Fritz-Joly Joachin, a Frenchman who reportedly had contact with one of the brothers involved in the fatal shootings at the Paris offices of Charlie Hebdo, was detained in Bulgaria on two arrest warrants, including one issued Monday, indicating that he planned to join a terrorist group, Agence France-Press reported Tuesday. Joachin had been held since Jan. 1 on a French-issued warrant amid claims from his wife that he kidnapped their 3-year-old son.

It’s unclear when authorities realized Joachin, 29, had a connection to one of the Kouachi brothers, who shot and killed 10 Charlie Hebdo journalists and two police officers in an attack on the Paris-based satirical magazine last week. But Joachin “was in contact with one of the two brothers -- Cherif Kouachi,” responsible for the Charlie Hebdo shootings, the public prosecutor in the Bulgarian capital of Sofia told AFP.

Bulgaria shares a border with Turkey, which in turn has a border with Syria that is used as a point to shuffle fighters and weapons in Syria’s long civil war. It was unclear whether Joachin was planning on joining the Islamic State, the militant group known as ISIS that has used the Syria-Turkey border to bring in fighters and weapons.

 "The charges are for participation in an organized crime group whose aim was organization of terrorist acts," said Bulgarian prosecutor Darina Slavova.

Joachin is a French citizen of Haitian origin who was in contact with Cherif Kouachi about a week before the Charlie Hebdo attack, according to AFP. He fled France for Bulgaria on New Year’s Day and wanted to enter Turkey.

Law enforcement zeroed in on Joachin when an arrest warrant was issued for him after his wife told authorities Dec. 30 that there was a strong chance that he would take their son to Syria, according to the Daily Mail. Joachin’s wife said he had converted to Islam 15 years ago and had recently become radicalized, the British tabloid reported. Authorities said Joachin was headed to Syria in part to attain education for his son on radical Islam.

Joachin told authorities in Bulgaria that he, his son and his girlfriend were in Istanbul for vacation. It’s unclear if Joachin was with a woman in Turkey.

Joachin’s extradition to France is expected to be decided on Friday. The 29-year-old has agreed to be sent back to France.