SOFIA, Bulgaria (AP) — The arrest in Bulgaria of a French citizen with ties to the attack on the Charlie Hebdo satirical newspaper in Paris followed a tip from his sister, new details showed Tuesday.

The arrest warrant issued by a French court for Mourad Hamyd was based on his sister Khadija's report to police that her brother had boarded a train via Hungary and Serbia to Bulgaria, even though he had told her he would travel to Morocco.

"This route corresponds with the route that is usually chosen by the jihadist volunteers that want to join the Islamic State group in Syria or Iraq," said the arrest warrant, which was made available to the AP Tuesday.

Hamyd, who was jailed in Bulgaria on July 29, is the brother-in-law of one of the men who attacked Charlie Hebdo in January 2015. He was initially suspected of a role in the attack on the paper, but his high school classmates launched a successful social media campaign to clear his name, saying he was in class at the time.

"I am a student who lives peacefully with his parents," he said then.

A court in the Bulgarian capital Sofia will hold a hearing on Wednesday on the European arrest warrant issued against him.

A court-appointed attorney said on Tuesday that Hamyd wants to return to France and that the court hearing is a standard legal procedure.

"The extradition has to be executed within a week. He could appeal the decision within three days, but he said that he doesn't intend to do so," Dragomir Alexandrov told The Associated Press.

Hamyd entered Bulgaria from Serbia on July 26, stating tourism as the reason for his one-week visit to Bulgaria. He had been travelling alone, with only personal luggage.

Rumyana Arnaudova, a spokeswoman for Bulgaria's chief prosecutor, said Bulgarian authorities received information through international channels that Hamyd was a traveling IS fighter and was considered to be "especially dangerous."